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Dualism of mind and matter in Buddhism
From a source which I don't remember any more (some rather scientific book on Buddhist philosophy) I have made a note, that the psyche in Buddhism is seen or can be seen (by certain schools?) as material.
To clarify this point for me, I wonder what the general treatment of mind and matter in Buddhism is, whether they are generally seen as two distinct spheres, how they interact, etc.

I think this question is a reason for the Mahayana split - the belief in cittamatra - mind only. I'm not sure if you want to get into the debate, or would rather pick a school and ask based on the teachings of that school. Just a heads-up that, as it stands, you'll probably get diverse and conflicting answers, as well (hopefully) as answers that describe multiple Buddhist views on the subject.

@yuttadhammo I would definitely want to know the traditional Theravada point of view. If I get more answers accordings to different traditions, even better: then maybe these answers already outline a historical development.

Nowhere I have seen idea in Buddhism that psyche is material. Nama-rupa division is standard. @yuttadhammo Reason for 'Mahayana split' is just acceptance of Mahayana canon or not. There is no theoretical split, as most Mahayana schools just inherited theory (as vinayas) of early sects. And they are very different, there is no united Mahayana philosophy. Fundamental idea of Mahayana is acceptance of any and *all Buddha's teachings. That's why canon is bigger and diverse.

The Nama-rupa division in itself does not establish an ontological status of nama. IWC the split, there IS a theoretical split. It has been shown that the Mahayana split was foreshadowed by the Mahasanghika split which was about doctrine and nothing else. And the reason for the Mahayana canon being inflated is an ongoing production of (pseudo-)suttas in the Mahayana at a time, when Theravada-canonification was long finalized.

Nama-rupa is not just division, it have explanation and commentaries. Check Nina van Gorkom writings, or Visudhimagga. What you remarked about Mahayana & split is very biased, shallow, and incorrect. Actual story is much more complicated, have many interpretations and different views.

@catpnosis I want to see some reasoning, some arguments in what concerns the Mahayana split. If it is incorrect, biased and whatever you claim, it should be easy for you, to prove me wrong...

@zwiebel I could argument, but this commentary thread probably isn't appropriate place. It was good to state we have different opinions, but to argue at length would be definitely off-topic for this question.

The Buddha of Pali Canon held an evidently pragmatic position, never explicitly defining his view as idealistic or materialistic. He does speak of "this body" as "composed of the four properties, born of mother & father, fed on rice & porridge, subject to inconstancy". He also speaks of consciousness as "dependent on body" and therefore impermanent, something a non-returner has fully realized. At the same time, for what looks like soteriological purposes, Buddha takes a fully phenomenological stance, speaking about skandhas and dhammas as constituting all of the (phenomenal) world.
After Buddha's death, this phenomenological perspective was a subject of abuse (IMHO) by generations of Abhidharmists indulging their analytical instincts. Their unchecked tendency to reify dharmas (assigning them the status of substantially existing) has led to emergence of Prajna-Paramita movement, the main point of which was assertion of philosophical relativism as fundamental principle underlying cognition. From this perspective, primacy of mind or matter is a matter of choosing a point of reference and has nothing to do with ontological state of affairs, which by its very nature is ineffable and is not subject to assertions.
In general, it looks to me like most Buddhist schools deny substantial dualism and either assert primacy of mind (Yogacara) or philosophical relativism (most of the rest of Mahayana). Theravada is a special case, torn between pragmatism and idealism, because it historically sees itself as results-oriented and not metaphysics-oriented, and at the same time carries on the legacy of Abhidharmic phenomenology. Vajrayana, being ultra-pragmatic liberation methodology, does not concern itself with such mundane affairs as mind/matter interaction, but we can say its position remains an extension of general Mahayana nondualism.
On top of this sedimentary layer of orthodox doctrines, lies a huge ocean of skilfull means, folk beliefs, and anecdotes, most of them implying naive dualism of crude matter and some kind of soul/mind substance, a perspective sharply criticised by many prominent teachers. For one example of the latter, see Dogen's "Soku Shin Ze Butsu" (Mind Here and Now Is Buddha).

Actually, "idealistic or materialistic" views are 'two extremes' which Buddha explicitly denied. "Abuse by generations of Abhidharmists" such a disrespect...

I think I agree with these statements ;)

The Buddha was empirical, not idealistic or materialistic. Discover the truth for yourself through samatha and vipassana.

@ruben2020 yes, I agree!

Any mind state and / or [metal factor][2] create some sensation or the other. These sensations can have some similarities exhibited by the 4 elements like pain (feels like Earth - gross solidified), vibrations, expansion contraction, etc.
What is experienced or felt is the mind. Hence there are times you feel the mind is turning to matter and matter into mind.

The Buddha described all of conditioned reality as nothing but the five skandhas, and subdivided those further (the experience of the body as earth element, fire element, wind.., water..). The khandhas are all of a type and are inconstant (always changing and not lasting forever), impersonal, and having the characteristic of dukkha (will cause suffering if clung to). These are the three marks of conditioned existence.
He also described the unconditioned, the unborn, the unmanifest, which cannot be perceived, conceived, or directly discussed or cognized. He was utterly a dualist. If you doubt this at all check out Buddhist scholar Ken Wheeler: https://youtu.be/FEnb2cFWKBs
That said, I would certainly not classify the dualism as mind/matter; one of the skandhas is consciousness. In my opinion, it is not rigorously, philosophically well defined as that was not his goal.

I marked this answer down because at least the Pali suttas say the unconditioned is perceived, cognized or known. Also, Ken Wheeler is a kook and is a non-Buddhist troll who I used to debate on a certain chatsite.

Thats a translation problem, it is not “perceived” as the samjna skandha of perception. Which if you think about it should be clear; the unconditioned is not a skandha. It is apprehended directly but not through samnja (perception). It is in a sense “felt” but not like the feeling skandha. There is not a good word for how it is “sensed” or known. It is beyond experience.

Sorry but your comment is unintelligible. If the unconditioned was not perceived by the Buddha, he could not have revealed it. The suttas literally say Nibbana is experienced. Please avoid posting unsubstantiated ideas. Thanks

The unconditioned is not a skandha. Perception is a skandha. It was not perceived in that sense. QED

Perception is a khandha. Perception of the unconditioned does not make the unconditioned a khandha. As I commented, many times, the suttas say Nibbana is experienced.

Also, there is not much point in answering questions that are 7 years old. Regards

For example the arupa jhana of neither-perception-nor-nonperception (which I spend a lot of time in, it is short of nibanna) obviously cannot be said to be perceived (just look at the name). So yes I am making perfect sense just beyond you.

Nibbana is not neither-perception-nor-nonperception nor cessation of perception & feeling. Your comment is 100% irrelevant. The suttas say countless times Nibbana is experienced.

Hi Al, welcome to the site. I thought I could mention, that you can address (reply to) comments if you find that helpful -- but that if you don't you can also ignore a comment, or flag it for moderators' attention.

@Dhammadhatu Apologies for rudeness. Ok We can disagree. Suttas never say nibanna is an object of perception (samjna). You may find a translation using the english “perceive” but thats not the best translation, because it will not be a form of the pali word samnja. Nibanna is not one of the skandhas nor “an object” of one of the skandhas. In neither-perception-nor-non, the meditator is neither perceiving nor non-perceiving, yet he knows he is in the state. We could say there is no object or that the object is mind (cit), but not “a state of mind” (as with a brahmavihara as object etc).

@ChrisW Thanks I appreciate the way you did that.   Yes I had realized I was being very silly. In fact I had the thought, “So we learn and meditate in order to become profound and right on the Internet to nameless people? Not to learn how to let stuff go and reduce suffering?” Lol.


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How did Buddha's teachings about samsara differ from earlier Indian tradition?
Even before the Buddha, the wheel of birth and death was a common teaching in India, with the six stages or realms. This is something that has passed down into Buddhism (even today). What did the Buddha add to this traditional teaching, and how does the Buddhist conception of samsara differ from this older teaching?

"From earlier Indian traditionS" as there was many traditions, even in Vedas.

@catpnosis I was using tradition as a mass noun, not a countable noun. "Indian tradition" can include all the different teachings, beliefs, folk wisdom, or cultural backgrounds from that region.

I’m not sure what you mean by six stages here.  Actually, it seems that the rebirth/samsara concept was not that old when Buddhism came on the scene.  Gananath Obeyesekere is an anthropologist who wrote a book about rebirth across a range of cultures.  He begins by trying to situate the Buddhist idea of ethical rebirth in the history of Indian religion:

I will begin with Hinduism and the problem of origins.  The association between karma and rebirth is not at all clear in the earliest texts and discourses on Indic religions.  There are virtually no references to rebirth or to an ethical notion of karma in the Vedas or in the BrāhmaNas, the oldest texts belonging to the Hindu tradition.  The first significant references appear in an early Upanishad, the BRhadāraNyaka UpaniSad, probably composed sometime before the sixth century BCE, followed by the Chāndogya and the KauSītaki.  A hundred years or more later these theories appear in full bloom in the so-called heterodox religions – particularly in Buddhism and Jainism – that have karma and rebirth at the center of their escatological thinking.  Soon afterward these ideas surface in mainstream Hinduism itself and become an intrinsic part of the eschatological premises of virtually all Indic religions.

Karma in the Vedas and karma in Buddhism are different:

The word karma, which etymologically means “action,” has the meaning of “ritual action” in Vedic (pre-Buddhist and pre-Upanishadic) thought, where it is neither fundamentally ethical nor related to rebirth.  By contrast, in Buddhism karma refers to intentional ethical action that determines the nature and place of rebirth, and this definition of karma has influenced the many Hinduisms that came after.

In The Wonder that was India, A. L. Basham writes about “transmigration” as a new development in Indic religion:

As Āryan culture pressed further down the Ganges it absorbed new ideas about the after-life.  In the Rg Veda the fate of the dead seems to have been finally decided when they died – they went either to the “World of the Fathers” or to the “House of Clay”, where they remained indefinitely.

Basham cites the same Upanishad text as Obesekere as the first appearance of the rebirth doctrine, but in a “primitive” form.  In this text, he points out,

this doctrine [...] is put forward as a rare and new one, and was not universally held at the time of the composition of the UpaniSad.  Even in the days of the Buddha, transmigration may not have been believed in by everyone, but it seems to have gained ground very rapidly in the 7th and 6th centuries BC.

It’s impossible for us to know if the rebirth concept came from some other tradition within India, since no texts have survived.  Anyway, it seems to have been “in the air” during the Buddha’s lifetime.  Probably the intellectual appeal of the concept, the justification it gives to ethical behavior, helped Buddhism spread and establish itself.  Also, the whole point of Obeyesekere’s book is that this idea is not unique to India – you also find it in Native American cultures, for instance.
Sources (bold text is my emphasis):
Gananath Obesekere, Imagining Karma:  Ethical Transformation in Amerindian, Buddhist and Greek Rebirth (U. of California Press, 2002), pp. 1-2.
A.L. Basham, The Wonder that was India, (Rupa 3rd ed., 1967), p. 242.

i want to let you know that Buddha was NOT born in India but in Nepal...!

It is unlikely that the Buddha pioneered the idea that karma determines rebirth or even rebirth itself, as Jainism already had it, and predates Buddhism.

One main distinction is that Buddha pointed out that the Devas and Brahma has a finite life where at that time some were aiming to be born in these relms believing that these planes are eternal.
Also another main distinction is that many believed in a eternal soul which is transmitted on death. Buddha rejected the existence of an everlasting soul travelling through Samsara.

The philosophy of transmigration is central to Buddhist philosophy and is to be understood alongside the concept of "no self".
But the origins of the concept of transmigration go way back further in time into the misty aeons of the Aboriginal spiritual practices on the Australian continent.
In fact the concept of rebirth appears always to be related to the beliefs surrounding the Nagas. In Australia the nagas materialise as the 'rainbow serpents' right across the country and the serpents are intricately involved with the rebirth of phenomena in one form or another and also are considered a manifestation of the underlying energies of the creative essence.
In fact the serpent figures feature prominently in ancient rock art considered to be in excess of 35,000 BCE showing a continuity of spiritual belief systems that challenge most current concepts of the evolution of spirituality and its origins.
I mention these facts only to illustrate that the Australian and Indian continents seem to share many primordial origins, but that's not relevant here.
The absence of the concept of 'non-violence' or of karmic ethics in Australia possibly points to the hunting/planting/gathering nature of the economic realities in Australia rather than the kind of spiritual evolution that agricultural and sedentary societies became capable of evolving on the Indian subcontinent in more recent times. Several anthropological studies have reflected on the comparable metaphysical capabilities of highly trained Australian adept/elders and counterparts in Vajrayana Buddhism in Tibet.
This is simply a clarification of the conceptual origins of transmigration rather than an observation on Buddhist philosophy but the relationship has for many years intrigued me as being more than just coincidental.

This doesn't answer the question, which asks for a comparison of the Buddha's conception of samsara with the earlier Indian tradition of samsara.

Welcome to the site, Chris. You might like to start by looking at the [help], which shows you how the Q&A nature of this site is different from a discussion site or forum. I thought your point was interesting and relevant, even if it was a bit of a tangent to the question.

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Does Theravada believe in feeding food to hungry ghosts?
Certain Buddhist schools perform rituals to offer food to hungry ghosts. And I've heard and read stories that psychic mediums at the rituals saw hungry ghosts came eating the food. Some also reported that they saw Buddha and Bodhisattas accompany the hungry ghosts.
I really wonder and would like to know if Theravada believes in these.

Theravada tradition believe in the transferring of merit to the deceased in case they are in need of merit. If born in a relm where you can sence and rejoice in the meritorious deeds performed you can gain merit. This does not imply that these beings are fed.
There is a Ancient India and Sri Lankan practice in doing leaving food for the Petas but this doesn't relate much to Buddhism. Ratana Sutta does mention harantia balin. So the Buddha did not reject it but I don't think this should be taken as an endorsement also by the Buddha. Hence this practice is outside Buddhism where Buddhism don't accept or reject the social practice at that time.

Yes, this tradition exists (existed?) among the Therevada as well:

The Petavatthu is a Theravada Buddhist scripture, .... It is composed
  of 51 verse narratives describing specifically how the effects of bad
  acts can lead to rebirth into the unhappy world of petas (ghosts) in
  the doctrine of karma.[1] It gives prominence to the doctrine that
  giving alms to monks may benefit the ghosts of one's relatives

http://en.wikipedia.org/wiki/Petavatthu

They stand outside our dwellings, at our windows, at the corners of our
  streets; they stand at our doors, revisiting their old homes. When
  abundant food and drink is set before them, by reason of the past sins
  of these departed ones, their friends on earth remember them not. Yet
  do such of their kinsmen as are merciful bestow upon them at due
  seasons food and drink, pure, sweet and suitable. Let this be done for
  your departed friends, let them be satisfied. Then, gathering together
  here, the assembled spirits of out kinsmen rejoice greatly in a
  plentiful repast. “Long,” they say, “may our kinsmen live through whom
  we have received these things: to us offerings are made and the givers
  are not without reward” for in the land of the dead there is no
  husbandry, no keeping of flocks, no commerce ad with us, no
  trafficking for gold: the departed live in that world by what they
  receive in this.  As water fallen upon a height descends into the
  valley, so surely do alms bestowed by men benefit the dead. As the
  brimming rivers fill the ocean, so do alms bestowed by men benefit the
  dead. Let a man consider thus—” Such a one gave me this gift, such a
  one wrought me this good deed; they were my kinsmen, my friends, my
  associates.” Then let him give alms to the dead, mindful of past
  benefits. For weeping and sorrow and all manner of lamentation are of
  no avail, if their relatives stand thus sorrowing it benefits not the
  dead. But this charity bestowed by you, well secured in the
  priesthood, if it long bless the dead, then does it benefit them
  indeed. And the fulfillment of this duty to relatives to the dead is a
  great service rendered, to the priests a great strength given, by you
  no small merit acquired (Petavatthu, Khuddaka pátha XII-XIII, trans.
  R.C. Childers)

ref: http://esoterx.com/2013/03/20/hungry-ghosts-the-diet-of-the-dead-among-the-grigori-preta-yidak-gaki-and-egui/

Benefit of ghosts (by giving alms to sangha) does not mean feeding ghosts. Benefit could be spiritual, as ghosts seems to be sensitive for intentions and wishes.

Found a quote, they did offer food to ghosts. All this said, working out the rules of magic regarding pretas is a bit like working out the rules of magic for zombies, which are different for Vikings, old movies and the most recent movies.

There is old movies and new movies. But there is also thousands years traditions too. You shouldn't put them on the same level.

The bold part of your quote is understood to mean "for the dead", as evinced by the story that prompted the verses: http://www.metta.lk/pali-utils/Pali-Proper-Names/tirokudda_s.htm Your translation appears to be a mistranslation of the dative, which can either mean "to" or "for"

Interesting. In any case, I'm sure people even back then saw that the food set out for hungry ghosts wasn't consumed, so however it worked, it would have been via folk magic.

What do you mean by Ghost, if Buddhism really talks about Ghosts?

@GokulNC Pretas, ref. https://en.wikipedia.org/wiki/Preta If you have a question about the role of pretas in Buddhism, post a question. There are many varieties of modern Buddhism, not all of them give the same importance or status to the realms myth or pretas (and the other fantastic creatures of Buddhist myths). StackExchange is about call Buddhist beliefs as they are and were, not to debate which sect is right.

A simple and direct answer is, 'Buddhism accepts the existence of ghosts and demons.' They are born as ghosts or demons because of their karma. Some demons are very powerful; they can even kill humans. They are powerful because of the good karma they accumulated in their early lives. However, if they use this power in a negative way, they will accumulate sins once again.
i heard some ghost/demon capable eat emotion as their meal. they strong when they absorb theses emotions.

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What/Who is 'Mara' in Buddhism?
Is there any definition for 'Mara' in Buddhism? Islam has a concept called Shayṭān. They explain it as the devil inside a human (Islam explanation). There is something like this in Christianity too. Does Mara represent the bad side of humans or is Mara understood differently in Buddhism?

Stephen Batchelor researched this and wrote a whole book on the "Devil" of Buddhist cosmology. I haven't read it yet: http://www.amazon.com/Living-Devil-Stephen-Batchelor/dp/1594480877

Mara viewed differently, depending on context, sometimes as type of living being and sometimes as personalization of Evil.

There are 5 kinds of Maras in Buddhism.

Khandha Māra - The five aggregates of clinging
Kilesa Māra - The defilements
Abhisankhāra Māra - The Karmic force
Maccu Māra - The death itself
Devaputta Māra - The god Mara who leads a faction in the Paranimmita-Vasavatti heaven.

I just have one more question. It says that the Arupa-loka beings are entirely of mind and cannot hear the dhamma. Then how do they practice?

They don't! They just enjoy the peacefulness of Arupa Jhana until their life runs out. They can practice in the next life.

Mara is seen as a tempter in some Buddhist texts perhaps personifying cravings and hindrances on the path. Perhaps I'll just highlight two references to Mara I am familiar with that point to this
The Enlightenment of the Buddha
During the Buddha's enlightenment Mara came to question, tempt and generally shake Siddhartha's (soon to be Buddha) confidence - sending women, firing missiles etc..
Finally he questioned Siddhartha's right to site on the spot under the Bodhi tree. The Buddha touch the earth as his witness and authority to sit there - put a bit more poetically here

Mara challenged Siddhartha--who will speak for you? Then Siddhartha
  reached out his right hand to touch the earth, and the earth itself
  roared, "I bear you witness!" Mara disappeared

This is why the Buddha is often seen touching the earth in pictures, rupas etc...
The Dhammapada
Another reference that points to Mara being more of a tempter rather than anything more comes from the flowers verses int the Dhammapada

. Realizing that this body is like froth, penetrating its mirage-like
  nature, and plucking out Mara's flower-tipped arrows of sensuality, go
  beyond sight of the King of Death!

I think it is notable (and evocative) that Mara is described as having flower tipped arrows. They are temptations that fly at you - more remeniscant of Cupid to my reading here.
So generally though I would hesitate to conflate Mara with evil (as in Satan) but maybe as own own internal obstacles and a personification of that.

Craving and hindrances fall under "Kilesa Māra". But "Devaputta Māra" is not a personification. He's a god leading a faction in the Tāvatiṃsa heaven.


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How do you repent in Chinese Buddhism?
Repentence is often mentioned in Mahayana texts. Outside of my knowledge of the meaning of the English word, which is colored by Christian concerns, I'm not sure what's involved. What is done during repentance? Is it just a matter of feeling sorry?

In Chinese Buddhism, repentance has two elements. The first:

One involves the rituals of confession in which we make offerings such as flowers and fruits to the Three Jewels as we sincerely confess and repent our sins. Through these rituals, we look honestly into our minds for the causes of our wrongdoings, sincerely accept responsibility for the harms we have caused, and resolve never to commit the same transgressions again.

And the second:

The other involves contemplation in which we reflect on the empty nature of all worldly phenomena, including our body, mind, and karma. When we keep our minds pure, clear, undisturbed by any thoughts, emotions and concepts, we will be able to transcend all karmic obstacles.

The formal process of repentance is achieved through the 88 Buddhas Repentance Ceremony:

In the 88 Buddhas Repentance Ceremony, participants repent by chanting the names of 88 buddhas, which is an excellent way to clear our karmic obstacles and draw out our inner wisdom.
  ...
  The power of chanting the buddhas’ names is documented in the past life story of Shakyamuni Buddha at the time of the Buddha Suryarasmi. One day, Shakyamuni Buddha, a practicing monk, heard the chanting of the 53 buddhas’ names and immediately sensed an indescribable joy, which he felt must be shared with all beings. He had the message passed along to 3,000 people, who followed his example and chanted the 53 buddhas’ names with deep respect and remembered each buddha’s name by heart. These people subsequently attained buddhahood in three different time periods, or kalpas.

And, importantly:

Shakyamuni Buddha also felt the suffering of beings who had to carry with them heavy karmic obstacles, so he taught them to repent by chanting the 35 buddhas’ names.

Here's a video of the ceremony itself:
https://www.youtube.com/watch?v=aCQia8XqOSo
Sources:
http://www.ctworld.org.tw/english-96/html/a13ceremony04.htm
http://www.ctworld.org.tw/english-96/html/a13ceremony06.htm

Platform sutra describes 'non-symbolic repentance' as including sincere promise to never repeat faults in the future, and acknowledgement of our past faults, that are caused by defilements of mind (ignorance, pride, and envy), which we decide to clean off our thoughts for good.


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What is a Vajrasattva?
I recently heard the term Vajrasattva and wondered if that is another term for a Bodhisattva?  How does the Vajrasattva path differ from the path of a Bodhisattva?

Vajrasattva is a specific bodhisattva, not another word for "bodhisattva." In esoteric traditions Vajrasattva is invoked as a counter measure to unwholesome actions. Esoteric traditions, and Tibetan traditions in particular, have elaborate explanations for the mechanics of karma+vipaka, and Vajrasattva is used as one of the opponent powers of confessing misdeeds. The general idea is that strong enough opposition to harmful deeds performed can circumvent the ripening of "bad karma" and prevent the formation of harmful habits and lower rebirths.


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Sutras in Western Buddhism?
How should western practitioners approach the sutras? What are the most important sutras from the main Buddhist traditions for westerners to study? When studying the sutras should that be considered a form of meditation?

Hinayana is not a main Buddhist tradition. But Theravada is.

Question so broad, so I'm curious how it could be answered. I can add to SankhaKulathantille's comment, that Vajrayana does not have sutras, their texts are called tantras.

We must not confuse Hinayana with Theravada because the terms are not synonymous. Theravada Buddhism went to Sri Lanka during the 3rd Century B.C. when there was no Mahayana at all. Hinayana sects developed in India and had an existence independent from the form of Buddhism existing in Sri Lanka. Today there is no Hinayana sect in existence anywhere in the world.

Voting to close. It's really broad and it is difficult to tell exactly what is being asked here.

I think this can be answered depemding on context you are practicing. I've put in an answer that is meaningful for me. I would also imagine that those more in the Secular Buddhism fold might have their own interesting take on this. I would leave this open

Your 3rd question would make a good question if you broke it out from the rest into a new question. (The "is reading sutras a type of mediation"-- on the amazon reviews for the Avatamsaksa sutra, someone suggested the best way to read it is like you're in a trance. Having read parts of it, I tend to agree, it sure isn't like reading a modern novel.)

@MatthewMartin  Sounds like a great idea.  I'll work on something.  The Avatamsaka Sutra is the Garland of Flowers, right?

I practice with the Triratna Buddhists which is an explicit attempt to bring Buddhism into the Western context. It is ecumenical so brings in all traditions so for me this question is very interesting. For us the sutras that are particularly studied are
Pali Canon
Middle Length Discourses generally but more specifically from the pali canon

Satipatthana sutta
Anapanasati sutta
Karaniya Metta Sutta
Dhammapada
Udana

Mahayana

Heart Sutra
Diamond Sutra
White Lotus Sutra
Vimalakirti Nirdesa Sutra
Golden Light Sutra

Also

Bodhicaryāvatāra
Life of Milarepa

This list isn't exhaustive by any means but I think represents the ones that are referenced most frequently. However a lot of others come up particularly from the Pali Canon such as the Gotami Sutta and even outside of Buddhism altogether such as the poetry of Rumi.

Since the question is broad my answer is opinionated towards the Theravada tradition.
Main aspect of Buddhism is that your practice should cover the 8 fold path (which is part of Bodhipakkhiyādhammā). Out of which a major part is meditation but ethics / morality is important.
Your choice of study ideally should cover the Bodhipakkhiyādhammā, Dependent Origination, and 4 Noble Truths. You should pick a set of Suttas covering these areas which suits your temperament.


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Buddhism in the Middle East
It is said, Buddhist missionaries made it to Alexandria Egypt and else where in the Mediterranean circa 200 BCE.   Have any scholars and/or archeologists found any evidence of Buddhism being practiced in the Eastern Mediterranean?

If anyone know, it's Donald Lopez, the man is a scholarship machine when it comes to digging up rare references to Buddhism far from it's ordinary home: http://www.amazon.com/Search-Christian-Buddha-Became-Medieval-ebook/dp/B00FQUDN44/

Im fairly sure its proven by archaeology that there were buddhist viharas in Alexandria as well as buddhist works in the great library of Alexandria.

I was reading about this because of the famous Milinda Questions. They are a set of questions asked by  Indo-Greek king Menander I (Pali Milinda) of Bactria from a 'Arhath' monk. Therefore it is possible that this Indo-Greek Kingdom probably had relations with both India and Mediterranean.

It is difficult to find archaeological evidence on this especially in the ME due to current situations. Also many might have been destroyed as Buddhism was there very early on.
But references like:

Suna paranthe
Yantatta Yonaka Pura Muninoca Padan
Ashoka's Dhammaduta routes
Attendees of Dhamma Sangayana

Point to some direction on this in literature. Evidence needs to be found though as I am not aware of any. (Perhaps some one can elaborate on this aspect.)


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If I undergo suffering now, will my next birth be better?
This answer points out that Karma is not something which is accumulated.
Hence considering karma as just cause & effect, if I undergo suffering now, like disease, disability, etc, will my future births be better since the cause has yielded a result and that cause is exhausted and will not influence my future births any more. So more suffering I undergo now, more causes I am exhausting ?

I never really understood this view, but it seems to have been held by the Niganthas. See MN 101 for a detailed argument against this sort of reasoning (too long to quote here).
Basically, though, it is like saying that if I have taken poison, I should take more poison so I feel the poisoning more quickly and thus somehow work out the result of the original poison quicker. Isn't that a ridiculous idea?
If I have performed karma X in the past that has result A in the future, performing other karmas Y and Z that also have result A doesn't do anything (except perhaps coincidentally - e.g. cutting off my arm means I can't experience pain in my hand) to affect karma X.
Another fallacy here is the idea that experiencing suffering leads to future happiness (in a way that pleasure doesn't). Really, to be objective, your question would have to include pleasure, in which case it would be, "If I undergo pleasure and pain in this life, will my next rebirth be better?" to which the answer is of course no.
An important concept to always keep in mind, according to the Buddha's teaching, is that pleasure and pain don't lead to pleasure or pain, it is good and evil that lead to pleasure and pain.

FYI: I'm upvoting your answers if I find them useful, even while posting my alternative answers.

Too bad I can't just copy and paste your answer onto the end of mine :)

Devadaha Sutta (MN 101) linked to by @Yuttadhamo is the right sutra to consider, that fully covers this topic. As you can see in MN 101, the Jains too held position that "burning" past karma through exertion and austerity can lead to liberation.
As he interrogates Jains, Buddha makes following points:

Not all pain comes from causes in the past. Some pain obviously comes from fierce striving, fierce exertion performed in the here-and-now. (As my first teacher used to say, sometimes pain comes from dental crowns and not from karma.)
Unfortunately, we can't really see how much negative karma we have accumulated, and how much karma has been exhausted so far.
If we saw that, then in theory we could talk about removing karma through exertion, similarly to how surgeon removes a poisoned arrow, producing pain short-term, but stopping it long-term.
Unfortunately, that is not possible, because:

Unfruitted karma that is to fruit in one way, cannot be converted to fruit in another way, through striving & exertion.
Unfruitted karma that is to fruit in the future, cannot be converted to fruit in the present, and vice versa, through striving & exertion.
Unfruitted karma that is to bring result of one size, cannot be converted to bring result of another size, through striving & exertion.

Instead, according to Buddha's teaching in MN 101, liberation from dukkha is achieved by "abandoning of unskillful mental qualities and the attainment of skillful mental qualities in the here-&-now".
Specifically, "skillful mental qualities" refer to 1) "exertion of fabrication against a cause of dukkha" which leads to "dispassion due to the fabrication", and to 2) "looking with equanimity at the cause of dukkha", which leads to "dispassion through the development of equanimity". In other words, cessation of dukkha is attained through 1) deliberate control of one's perspective, and through 2) equanimity that comes from philosophical attitude.
As an example of typical dukkha-pattern, Buddha tells a story of unshared love, with the protagonist suffering from "sorrow, lamentation, pain, distress, & despair" due to being "in love with her, his mind ensnared with fierce desire, fierce passion". The protagonist then wilfully abandons "desire & passion for that woman" (an effort that serves as "exertion of fabrication against a cause of dukkha") and as a result attains dispassion "due to the fabrication".
With all of the above in mind, Buddha still admits to importance of pushing oneself and overcoming one's limits -- to avoid regress due to indulgence -- but only inasmuch as to have "unskillful qualities decline" and "skillful qualities increase":

So he exerts himself with stress & pain, and while he is exerting
  himself with stress & pain, unskillful qualities decline in him, &
  skillful qualities increase. Then at a later time he would no longer
  exert himself with stress & pain. Why is that? Because he has attained
  the goal for which he was exerting himself with stress & pain.

As a result,

A monk, when not loaded down, does not load himself down with pain,
  nor does he reject pleasure that accords with the Dhamma, although he
  is not fixated on that pleasure.

Since there are great answers already, I won't be answering. So consider this not as an answer but as an appendix that might help you discern the details of the answers.

MN 14, The Shorter Discourse on the Mass of Suffering (Cūḷadukkhakkhandha-suttaṃ)
MN 45, The Shorter Discourse on Ways of Undertaking Things (Cūḷadhammasamādāna-suttaṃ) *
MN 46, The Greater Discourse on Ways of Undertaking Things (Mahādhammasamādāna-suttaṃ) *
MN 101, To Devadaha (Devadaha-suttaṃ)

* These discourses seem to answer the question directly.

If an individual is suffering because they are overcoming the five hindrances than probably. If a person is suffering because they are indulging in the five hindrances than probably not.
If I eat a big plate of my favorite food every night I will suffer from it because there will be times when I am not eating it, there are times I will feel sick from too much of it and many other ills associated with the indulgence. This suffering (unless it leads to the eventual cessation of desire in regards to this food) will not help my future births.
If I am addicted to eating my favorite food every night and I realize how foolish it is to indulge in it, and I decided to stop, I will suffer during the process of overcoming this attachment. This suffering will help my future births.
In regards to OP's comment: A person who recently got a disease would not have any more inherent suffering in their life than someone who did not have a disease given that they are clear of the hindrances.
The suffering is compounded when the individual desires feeling good and healthy (sensory desire), or is worried about death or further illness (worry), or is angry that they are sick when someone else they know deserves it more (ill-will), etc, etc.... That type of suffering, the same as in the example regarding food, will not help; overcoming attachments to these hindrances can incur a lot of suffering (I am not my good health, I am not worried about "death", no one deserves anything, etc, etc...; respectively) and that suffering can help future rebirths.

Thank you for the answer. I meant, getting a disease unexpectedly without indulging in the 5 hindrances.

Karma is of course accumulated. But other factors play much more important role in it's ripening than exhausting of accumulations. Our actions in this life and (impossible to control) thoughts at the last moments of life are usually much more determinant to next birth than expiration of karma or merit. See quotation from Abhidharmasamuccaya:

A being is accompanied by many actions. In this case, what is the
  order of results of maturation?
i) First to produce its results is the most serious action;190
ii) next, the action that appears at the moment of death;191
iii) then, that which was habitually done previously;192
iv) finally, that which was done earlier in a past lifetime.193
(footnotes):
[190] Pradhan’s restoration: audārika-karma. But very probably
  guru-karma. Cf. Kośa, IX, 297. In Pali also it is garu- or
  garuka-kamma. [191] Āsanna- or maraṇāsanna-kamma in Pali. [192] In
  Pali ācinnaka- or bahula-kamma. [193] This refers to kaṭakka-kamma in
  Pali . These four actions produce their results in this order. Serious
  action has priority over the others. If there is no serious action,
  then an action which presents itself to the mind at the moment of
  death produces its results. If no particular action presents itself to
  the mind at the moment of death, then the action most frequently done
  produces its results. If none of these three actions has the
  opportunity of bearing results, then an action done in a past lifetime
  will produce its results. See Kośa, IX, 297.

To rely on expiration of karma is probably even wrong view, because it is conductive to lack of right effort to do wholesome actions that actually improve karma.
Also, without right effort you'll continue to produce bad karma so there is no exhaust in this case.

"Karma is of course accumulated" Where and by who?

I think Karma is accumulated as a potential. If I cause Dukha to someone, then it creates a potential for Dukha for me. And when the conditions are right, the potential is transformed into  action causing me pain & suffering. Maybe my reasoning isn't quite right. But  this is what I infer.

@yuttadhammo This answer may be helpful for you http://buddhism.stackexchange.com/a/147/145

I have downvoted this answer as well. Karma does not "accumulate" it simply is action yet-to-fruit as result. Most importantly, this answer misrepresents Buddhist attitude to Liberation, which is achieved by "abandoning of unskillful mental qualities and the attainment of skillful mental qualities in the here-&-now", not by exhausting bad karma or accumulating good karma.

@zvolkov I know of this danger and didn't misrepresent Buddhist attitude or teaching. Did you read it to the end?

@zvolkov Btw, 'accumulate' is just a word, how can you prove that this word can not be applied to karma? For example, definition of accumulate: 'gather together or acquire an increasing number or quantity of'. If action doesn't accumulate then it's lost, then there is no merit, no practice of accumulation of merit is possible. If you did two wholesome actions shouldn't you get two wholesome fruits? If yes, then it's accumulated.

This from Bodhidharma

Every suffering is a buddha-seed, because suffering impels mortals to
  seek wisdom. But you can only say that suffering gives rise to
  Buddhahood. You can’t say that suffering is Buddhahood. Your body and
  mind are the field. Suffering is the seed, wisdom the sprout, and
  Buddhahood the grain. The Buddha in the mind is like a fragrance in a
  tree. The Buddha comes from a mind free of suffering, just as a
  fragrance comes from a tree free of decay. There’s no fragrance
  without the tree and no Buddha without the mind. If there’s a
  fragrance without a tree, it’s a different fragrance. If there’s a
  Buddha without your mind, it’s a different Buddha

Emphasis mine.
Given the conventional theory of karma (the actor is not different to who experiences the result) it seems like you're asking whether bad karma can ever be exhuasted. I would say yes. There's definitely an imperative to avoid both extremes (austerities and indulgence), though, even if that only applies to those on the path, which it likely doesn't anyway


text:
What is the source of these "Lay Bodhisattva Vows"?
Okay, I'm well familiar with the regular Bodhisattva vows from the Brahma Net Sutra. That set of vows is open to both lay and monastic followers.
I just found another set on Dharma Realm Buddhist Young Adults and I can't figure out where they come from (which sutra).
Full text linked below. It has 6 major and 28 minor precepts. It has precepts like, 21st-- pay your taxes and 27th-- don't raise silk worms.
Is this a modern set of precepts or does it have a older origin?
ref:
http://www.drby.net/attachments/035_The%20Bodhisattva%20Precepts%20for%20Laypeople%20-%20English.pdf
(Above PDF came from this link: http://www.drby.net/index.php/Events/Lay-Bodhisattva-Precepts-Transmission.html )

Okay I found the answer.
It's from the "Sūtra of the Upāsaka Precepts" (Shansheng Jing). It was translated into Chinese in the 5th century.
http://www.sutrasmantras.info/sutra33c.html
This sutra has similarities to the older Sigalovada Sutta http://www.accesstoinsight.org/tipitaka/dn/dn.31.0.ksw0.html
(Ref comparing the UPS and Sigalovada: "Buddhism and Peace", chapter 10)


text:
What is the oldest text/sutra of the Mahayana tradition?
I'm often interested in the history of Buddhist texts and, being a Theravadan, I'm not very familiar with the Mahayana texts. Please help to educate me in this manner.

The oldest existing manuscript clearly identified as Mahāyāna is a birch bark manuscript of the Aṣṭasāhasrikā-prajñāpāramitā-sutra or Discourse on Perfect Wisdom consisting of 8000 [Lines]. This manuscript was carbon dated to  47~147 CE. A version of this text was translated into Chinese in 179 CE by Lokakṣema and was amongst the first few Buddhist texts translated into Chinese.
However it's clear that some texts were being composed at quite an early period, perhaps as early as the 2nd Century BCE. One contender for the earliest Mahāyāna text is the Ugraparipṛccha, translated by Jan Nattier as A Few Good Men (2003). It shows a very early stage of Mahāyāna in which monks who dedicated themselves to meditation were known as bodhisatvas and lived alongside Mainstream monks.
Another serious contender is the Śālistamba Sūtra (translation published by N Ross Reat, 1993), which is clearly a little more developed than early Buddhist texts, but not yet a full-blown Mahāyāna text. It may well be considered a kind of "missing link" between the two phases of Buddhism. According to N. Ross Reat, the sutra could date as far back as 200 BCE.
Recently there were two very good articles on the very early Mahāyāna by David Drewes. See his academica.edu page "Early Indian Mahayana Buddhism" Parts I & II.

While there is no commonly recognized single oldest Mahayana sutra (see Wikipedia for general treatment of the topic), many scholars and practitioners believe some of the Prajnaparamita-series sutras to be very old.
Specifically, Aṣṭasāhasrikā Prajñāpāramitā Sūtra ("Perfection of Wisdom in 8,000 Lines") is believed to be written as early as 1st century BCE -- the earliest date I have personally seen anywhere for a Mahayana sutra. This sutra exists in two versions, one in verse and one in prose. As per Edward Conze, "for early Mahayana sutras that was quite a normal procedure."
The verse version is known as Prajnaparamita-Ratnagunasamcayagatha or simply "Ratnaguna". Based on linguistic analysis, Ratnaguna is thought to be the earlier of the two. According to Edward Conze, Ratnaguna's first 41 stances, known separately under the name of "Arya Prajna-Paramita Carya Gatha", are the earliest core. This makes Arya Prajna-Paramita Carya Gatha a good contender for a honorary title of the earliest Mahayana sutra.
It is available here as part of Edward Conze's complete translation of Ratnaguna and here translated by a committee under guidance of 16th Karmapa. Here I am posting my amateurish translation of the first 8 verses from BHS:

Super-loving-dear-grate-ful mood having established,
  Having stopped sustaining the blinding emotions (avarana-klesha),
  Listen carefully, oh the best of having gone forth
  after Transcendental Wisdom, sages.
Any rivers flowing here in Jambu-dvipa (India)
  Fruits-and-flowers, trees-and-grasses grow from which,
  -- of the Mountain Dragon are running tears,
  To his womb's grace this realm owes its existence.
Any Dharma declaring students of Victor,
  Illuminating logically, cohesively, also elaborately,
  And other people, fruit of happiness, through that work, attaining
  -- of all these the producer is Tathagata.
What came from Victor, having spoken the guidebook of Dharma,
  Following those instructions the best students acquire,
  And from direct experience, as have seen, proclaim:
  The state of Buddha is not a state of supermanly powers.
In it there is no acquisition of "Transcendental Wisdom" (Prajna-Paramita),
  Also, no "Bodhisattva attainment", no "Enlightenment" of the mind.
  -- This having heard but not confused nor panicking,
  Bodhisattva engages in wisdom of the Lucky Ones (sugatas).
Also, not of body, nor feelings, nor thoughts, nor volitions,
  Nor of consciousness, position even a little do not bother him.
  Thus, to all dharmas not getting stuck, not getting caught into traps of abstractions (aniketacari)
  Not clinging, he attains awakening of the Lucky Ones.
As venerable Shrenika the wandering beggar,
  Understanding acquired, without precisely grasping the skandhas,
  Just so bodhisattva, intuits real nature of things (dharmas).
  And does not seek cessation (nirvritti) but abides in wisdom.
Having stopped again and again wavering searching for wisdom,
  "Whence?", "Why?" -- of such dharmas empty,
  Having stopped getting upset, caught up, or scared,
  Soon he can reach awakening, such Bodhisattva.

Ratnaguna is separate text from the Astasahasrika, and the 'first 41 stances' is two chapters from Ratnaguna, not from Astasahasrika.

Yes, Ratnaguna is a verse version of Astasahasrika, I thought I made that clear: "Of this sutra, according to Edward Conze, the first 41 stances of the verse version, known as Prajnaparamita-Ratnagunasamcayagatha...". I guess this is not clear enough, sorry let me rephrase.

Done. Is it better now?

Probably. But I still wonder how Conze come to conclusion that this is the "same text". Because they are very different texts: different length, different in being prose and poetry, different in content and meaning. It is not the case that Asta was just put into verses. Buddha says different things there. Yes, they have similarities, but this doesn't warrant being called same text.

@catnopis Actually the form of Rgs is very similar to Aṣṭa: the subjects occur in much the same order. One can frequently trace actual quotes common to both texts (I have done so: http://jayarava.blogspot.co.uk/2014/08/roots-of-heart-sutra.html). The relationship is similar to that between Aṣṭa and the 25k line text. It's one text constantly reworked and elaborated. The idea of the verse being earlier is not based on solid evidence, it's the kind of intuitive guess that blights much of Conze's work. The oldest extant manuscript is the prose text in Gāndhārī.

That's quite a broad question, I certainly can't give it justice, but here are some starter points while we wait for better answers:
Mahayana Texts are preserved either via the Chinese Canon or the Tibetan Canon and certain of them were probably written outside of India.
These text were not memorized, these almost certainly were composed-- they are just too long to have been memorized.
They are in a completely different style-- attempting to imbue a sense of awe and wonder. I can't say it always works for me, some texts can get rather tedious in their "better than infinity plus one" exaggerations.
They tend to follow a pattern-- it starts out describing the Buddha getting ready to deliver a teaching, describes who is in attendance, and so on.  The often include large sections about the merits of making copies of the sutras.
Thematically, I definitely don't have time to do them justice, they cover a lot of different themes. Some describe mantras and their benefits. Some describe Bodhisattva's-- their previous lives as monks and the various heroic vows they made.  Some of them are philosophical discussions, sort of like Plato's dialogs.
The tantras sometimes get included in the broader category of Mahayana texts, but I haven't tried to read the tantras yet.

is there one, or a grouping or some that are considered by Mahayana scholars to be the oldest in terms of when they came about?

Ajitasena Sutra, recently discovered in Afganistan, ref: http://en.wikipedia.org/wiki/Mah%C4%81y%C4%81na_s%C5%ABtras#Proto-Mah.C4.81y.C4.81na_s.C5.ABtras I can't say I know anything about it. The next famous sutras are the samadi and prajnaparamita sutras.

Plenty of Mahāyāna texts are preserved in Sanskrit, so it's not correct to say either via the Chinese Canon or the Tibetan Canon. There is an active tradition of copying Sanskrit manuscripts in Nepal for example.

Keeping dependent arising in mind.  The Gandharan Buddhist texts according to scholars contain samples of ancient Mahayana texts and teachings from the Dharmaguptaka school, the discovered texts have been dated to the 1st century CE.  "Whose Buddhism in Truest?" an article written by Linda Heuman in Tricycle Magazine provides insightful information regarding these early texts and possible ramifications regarding the development of Buddhist traditions.

license: Creative Commons - Attribution Share-Alike - https://creativecommons.org/licenses/by-sa/4.0/


text:
Why does the Buddha call himself the Tathāgata?
Questions in the title. What is the significance of this term and how it is used by the Buddha in the suttas?

From an academic perspective the wikipedia article "Tathāgata" has good information. According to wikipedia:
The word's original significance is not known and there has been speculation about it since at least the time of Buddhaghosa, who gives eight interpretations of the word, each with different etymological support, in his commentary on the Digha Nikaya, the Sumangalailasini:

He who has arrived in such fashion, i.e. who has worked his way upwards to perfection for the world's good in the same fashion as all previous Buddhas.
He who walked in such fashion, i.e. (a) he who at birth took the seven equal steps in the same fashion as all previous Buddhas or (b) he who in the same way as all previous Buddhas went his way to Buddhahood through the four Jhanas and the Paths.
He who by the path of knowledge has come at the real essentials of things.
He who has won Truth.
He who has discerned Truth.
He who declares Truth.
He whose words and deeds accord.
The great physician whose medicine is all-potent.

Modern scholarly opinion generally opines that Sanskrit grammar offers at least two possibilities for breaking up the compound word: either tathā and āgata or tathā and gata. Tathā means thus in Sanskrit and Pali, and Buddhist thought takes this to refer to what is called reality as-it-is (yathā-bhūta). This reality is also referred to as thusness or suchness (tathatā) indicating simply that it (reality) is what it is.
A Buddha or an arahant is defined as someone who "knows and sees reality as-it-is" (yathā bhūta ñāna dassana). Gata "gone" is the past passive participle of the verbal root gam "go, travel". Āgata "come" is the past passive participle of the verb meaning "come, arrive".
Thus in this interpretation Tathāgata means literally either “the one who has gone to suchness” or "the one who has arrived at suchness".
Another interpretation, proposed by the scholar Richard Gombrich, is based on the fact that that, when used as a suffix in compounds, -gata often loses its literal meaning and signifies instead "being". Tathāgata would thus mean "one like that", with no motion in either direction.
According to Theodore Stcherbatsky, the term Tathagata has a non-Buddhist origin, and is best understood when compared to its usage in non-Buddhist works, such as the Mahabharata. Stcherbatsky gives the following example from the Mahabharata:

Just as the footprints of birds (flying) in the sky and fish (swimming) in water cannot be seen,
    Thus (tātha) is going (gati) of those who have realized the Truth.

Buddha uses the term to refer to himself rather than saying, I, me or myself.

Mahabharata is obviously post Buddhism. Also, the word gati appears to be a verb.

Tatha means "truth", "reality" or literally "so", "such".
gata is often translated as gone, however from my research it looks like it is a suffix that means "firmly grounded in" or "rooted in" -- as in kayagata smrti "mindfulness rooted in the body".
Together this would make Tathagata mean "Firmly established in reality".
I personally associate this word with two other terms: sugata and duggata.
Sugata is a person who fared well, a lucky one, and therefore an optimist.
Duggata is an unfortunate person, a loser, and therefore a pessimist.
Tathagata would then mean neither a pessimist nor an optimist, but realist.

Or for example "ārāma-gata, mfn., having gone to or being in a monastery" -- saying that "gone to" and "being rooted in" are the same.

https://suttacentral.net/dn29/en/sujato

how about interpreting ‘gata’ or ‘gone’ as past participles in other Indo-European languages: ‘well-behaved’ meaning ‘behaving well’, or ‘ill-mannered’ etc?  then ‘tathagata’ means simply one who goes by reality/truth, sticks to reality/truth. well I guess full mindfulness amounts to the same.

reasonable answer but rather tenuous statement derived from kayagata smrti. Mindfulness cannot be rooted in the body. Mindfulness means remembrance. Mindfulness can only recollected mental phenomena.

Repeating a poem to learn it by rote is also called sati/smrti. Repeating recollection of applying attention to the bodily phenomena is mindfulness rooted in the body, established onto the body.

1. Why does the Buddha call him self Tathāgata?
What would be better than showing the man's own words?

"Whatever in this world — with its devas, Maras, & Brahmas, its
  generations complete with contemplatives & brahmans, princes & men —
  is seen, heard, sensed, cognized, attained, sought after, pondered by
  the intellect, that has been fully awakened to by the Tathāgata. Thus
  he is called the Tathāgata.
"From the night the Tathāgata fully awakens to the unsurpassed Right
  Self-awakening to the night he is totally unbound in the Unbinding
  property with no fuel remaining, whatever the Tathāgata has said,
  spoken, explained is just so (tathā) and not otherwise. Thus he is
  called the Tathāgata.
"The Tathāgata is one who does in line with (tathā) what he teaches,
  one who teaches in line with (tathā) what he does. Thus he is called the
  Tathāgata.
"In this world with its devas, Maras, & Brahmas, its generations
  complete with contemplatives & brahmans, princes & men, the Tathāgata
  is the unconquered conqueror, all-seeing, the wielder of power. Thus
  he is called the Tathāgata.
  -Iti 4.13, Discourse on the World (Lokasuttaṃ)

In addition to the above, DN 29 provides one more definition:

'If "the past" refers to what is not factual, not true (atathā), to what is
  not of advantage, the Tathāgata makes no reply. If it refers to what
  is factual, true (tathā), but which is not of advantage, the
  Tathāgata makes no reply. But if "the past" refers to what is factual, true (tathā), and which is of advantage, then the Tathāgata
  knows the right time to reply. The same applies to the future and the
  present. Therefore, Cunda, the Tathāgata is called the one who
  declares the time, the fact, the advantage, the Dhamma and the
  discipline. That is why he is called Tathāgata.'
  -DN 29, Delightful Discourse (Pāsādika-suttaṃ)

2. What is the significance of the term?
As the Wikipedia states:

Modern scholarly opinion generally opines that Sanskrit grammar offers
  at least two possibilities for breaking up the compound word: either
  tathā and āgata or tathā and gata. Tathā means thus in
  Sanskrit and Pali, and Buddhist thought takes this to refer to what is
  called reality as-it-is (yathā-bhūta). This reality is also referred
  to as thusness or suchness (tathatā) indicating simply that it
  (reality) is what it is.
A Buddha or an arahant is defined as someone who "knows and sees
  reality as-it-is" (yathā bhūta ñāna dassana). Gata "gone" is the past
  passive participle of the verbal root gam "go, travel". Āgata "come"
  is the past passive participle of the verb meaning "come, arrive".
Thus in this interpretation Tathāgata means literally either “the one
  who has gone to suchness” or "the one who has arrived at suchness".
  -Tathāgata Wikipedia Page

So it appears these two meanings can be derived from the word. I think some light can be shed by seeing the word used in another context in which there can only be one meaning due to the nature of it's context (simile):

In ancient times when seafaring merchants put to sea in ships, they
  took with them a bird to sight land. When the ship was out of sight of
  land, they released the bird; and it flew eastward and westward,
  northward and southward, upward and all around. And if the bird saw no
  land, it returned to the ship; but if the bird sighted land nearby, it
  was truly gone (tathāgatakova).
  -AN 6.54, Discourse about Dhammika (Dhammika-suttaṃ)

Note that footnote nº2 of the above discourse is also worth reading to get a better grip on it's meaning.
3. How is the term used by the Buddha in the suttas?
As user70 pointed out, the Buddha usually uses the term to refer to himself. Above, I quoted a number of prosaic contexts that reveal how he uses the term, so I'll leave a poetic reference for this answer.
    Just this
    is the path
 - there is no other -
to purify vision.
    Follow it,
and that will be Mara's
    bewilderment.

Following it,
you put an end
to suffering & stress.
I have taught you this path
having known
 - for your knowing -
the extraction of arrows.

It's for you to strive
    ardently.
Tathāgatas simply
point out the way.
Those who practice,
absorbed in jhana:
    from Mara's bonds
    they'll be freed.

-Dhp v275-276

Excellent quotes.

A Tathagata is one who is neither coming or going. That is neither going to the other side or coming back. Because there are no longer sides. Just what is.

tathāgata
tatha: (being) in truth，truthful； true，real
ā: to，towards
gata: directed to
*canonics

Unrul3r's answer includes that it might mean going or coming (gata or agata).
Andrei's answer is that it means 'grounded' or 'rooted' (which makes sense to me: because if you go or come, have gone or have come, to somewhere then that is where you are).
Combined (and further to user319's answer) these remind me of a Zen story --  using Google I cannot find a reference to it at the moment, so I paraphrase it:

Someone, who is dying, says, "We come from nowhere, and we go to nowhere."
His companion, to be helpful, replies, "Let me show you the road, where there is no 'coming' and no 'going'."

Tathagata is one who will not be reborn. In the Sutta the word is used only for Sammasambuddha. It cannot be separated as Tatha + Agata; or Tatha + Gata. It is Tathaa + gata.
A Tathagata has stopped 'moving' is Sansara.

Hello. The suttas literally say the Tathagata is not not-reborn. MN 72 says ‘They’re not reborn’ doesn’t apply, Vaccha.” “Na upapajjatīti kho, vaccha, na upeti”.

My guess for this question is Tathāgata means "arrived at/come to the truth/reality".
The Pali Dictionary say the origin & etymology of Tathāgata is unknown, including to Buddhaghosa:

Derivation uncertain. Buddhaghosa (DN-a.i.59–DN-a.i.67) gives eight
explanations showing that there was no fixed tradition on the point,
and that he himself was in doubt.

It appears there are two possible derivations:

tatha + āgata = reality/truth come/arrived
tathā + gata = thus gone

The seemingly unambiguous contextual non-Buddha use of the term in AN 6.54 seems to explain the term, as follows:

“Sir, I’ve been banished by the local lay followers from all seven
monasteries in my native land.”
“Pabbājito ahaṁ, bhante, jātibhūmakehi upāsakehi sabbaso jātibhūmiyaṁ
sattahi āvāsehī”ti.
“Enough, Brahmin Dhammika, what’s that to you? Now that you’ve been
banished from all of those places, you have come to me.
“Alaṁ, brāhmaṇa dhammika, kiṁ te iminā, yaṁ taṁ tato tato pabbājenti,
so tvaṁ tato tato pabbājito mameva santike āgacchasi.
Once upon a time, some sea-merchants set sail for the ocean deeps,
taking with them a land-spotting bird.
Bhūtapubbaṁ, brāhmaṇa dhammika, sāmuddikā vāṇijā tīradassiṁ sakuṇaṁ
gahetvā nāvāya samuddaṁ ajjhogāhanti.
When their ship was out of sight of land, they released the bird.
Te
atīradakkhiṇiyā nāvāya tīradassiṁ sakuṇaṁ muñcanti.
It flew right away to the east, the west, the north, the south,
upwards, and in-between.
So gacchateva puratthimaṁ disaṁ, gacchati pacchimaṁ disaṁ, gacchati
uttaraṁ disaṁ, gacchati dakkhiṇaṁ disaṁ, gacchati uddhaṁ, gacchati
anudisaṁ.
If it saw land on any side, it went [arrived] there and stayed.
Sace [if] so [he; the bird] samantā [everywhere] tīraṁ [shore] passati [sees], tathāgatako [truely arriver/comer] va hoti [is a].
But if it saw no land on any side it returned to the ship.
Sace pana so samantā tīraṁ na passati tameva nāvaṁ paccāgacchati.
In the same way, now that you’ve been banished from all of those
places, you have come to me.
Evamevaṁ kho, brāhmaṇa dhammika, yaṁ taṁ tato tato pabbājenti so tvaṁ
tato tato pabbājito mameva santike āgacchasi.

āgacchati = comes,
comes near; comes back, returns; reaches, attains, arrives
pp āgata

Alternately, the independent Australian translator Sujato on Sutta Central asserted the use of "tathāgata" in AN 6.54 is unrelated to the use of tathāgata as the Buddha's name. The impression is, for Sujato, tathāgata as the Buddha's name means "arrived/come to the truth" but in AN 6.54 tathāgata means this bird has "thus gone/flown". Sujato said:

Oh, and to forestall the obvious, no this doesn’t have anything to do
with tathāgata as an epithet of the Buddha. The terms in this compound
are extremely common and occur in a wide variety of senses. As an
epithet of the Buddha, the primary sense is “one who has realized the
truth”. How to translate ‘tathāgatakova’?

To me, it seems plainly obvious the analogy in AN 6.54 logically is about the bird & thus the ship arriving/coming to land, just as the ex-Brahmin had come to the Buddha. There is the word 'āgacchati' about the ex-Brahmin coming to the Buddha and the past participle of āgacchati, namely, āgata, in the term 'tathāgatakova' about the bird/ship coming/arriving to land.
To conclude, for me, Tathagata means 'come to the truth'; derived from tatha + āgata.
Thus Iti 112 says, per Sujato translation:

In this world—with its gods, Māras, and Brahmās, this population with
its ascetics and brahmins, its gods and humans—whatever is seen,
heard, thought, known, attained, sought, and explored by the mind, all
that has been understood by the Realized One.
Yaṁ, bhikkhave, sadevakassa lokassa samārakassa sabrahmakassa
sassamaṇabrāhmaṇiyā pajāya sadevamanussāya diṭṭhaṁ sutaṁ mutaṁ
viññātaṁ pattaṁ pariyesitaṁ anuvicaritaṁ manasā yasmā taṁ tathāgatena
abhisambuddhaṁ,
That’s why he’s called the ‘Realized One’.
tasmā ‘tathāgato’ti vuccati.
From the night when the Realized One understands the supreme perfect
awakening until the night he becomes fully extinguished—in the element
of extinguishment with nothing left over—everything he speaks, says,
and expresses is real, not otherwise.
Yañca, bhikkhave, rattiṁ tathāgato anuttaraṁ sammāsambodhiṁ
abhisambujjhati, yañca rattiṁ anupādisesāya nibbānadhātuyā
parinibbāyati, yaṁ etasmiṁ antare bhāsati lapati niddisati, sabbaṁ taṁ
tatheva hoti no aññathā,
That’s why he’s called the ‘Realized One’.
tasmā ‘tathāgato’ti vuccati.
The Realized One does as he says, and says as he does.
Yathāvādī, bhikkhave, tathāgato tathākārī, yathākārī tathāvādī,
Since this is so,
iti yathāvādī tathākārī yathākārī tathāvādī,
that’s why he’s called the ‘Realized One’.
tasmā ‘tathāgato’ti vuccati.

I cannot seem to find in which Sutta this is said, but...
The Blessed One said once: Bhikkhus, the world has been discovered by the Perfect One, he has dissociated from the world. The origin of the world has been discovered by Him. He has abandoned the origin of the world. The cessation of the world has been discovered and He has realised the truth. In the world with its deities and others, whatever can be seen, heard sensed and cognized or reached, sought out and encompassed by the mind, has been discovered by the Perfect One that is why He is called a Perfect One (The Thathagatha). The Most Enlightened.


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How closely related are the concepts of Karma and Pavlovian conditioning?
If I get into a habit of fighting to defend "my self" is it reasonable to say that getting into a fight and getting beat up is karma?
How similar is karma to the idiom "you reap what you sow"?

How closely related your question in the title with question details?

They are related in that they are all an attempt to enlighten myself to the notion of karma. On the other hand you make a good point, the details do not necessarily elaborate on the title question.

While habits are part of the workings of karma, it is not reasonable to say that what you described (habit to fight leads to beating) is Buddhist notion of karma. It may be correct other way around, though—some unwholesome karma is ripening while you exercise habit to fight.
Karma is similar to idiom "you reap what you sow" but with some added complexity. What you will reap is not need to be the same or feel the same as what you sow. In Buddhist concept of karma, unwholesome actions, when sown, will certainly reap into unwholesome fruits. What will be reaped is not mirror of what is sown, but it is consequence of what was sown. So when you sow action that should result in suffering, you will reap suffering for sure.

Kamma is a natural law.
Pavlovian conditioning is men-made.
The habit to fight is, by the way, not necessarily a Pavlovian conditioning.

Fighting to defend one's sense of self would be would it not? Having defended the sense of self is the reward thus the behavior of fighting is strengthened.

No, it's not. Pavlovian conditioning is behavioral modification. Done by linking two stimuli that have nothing to do with each other before the conditioning takes place. Think of the sound of the bell (the first neutral stimulus) and the salivating of the dog (which is a natural, automatic response). The linking of the two is the Pavlovian conditioning.
If I were to condition you to fight for your sense of self every time I snap my finger or someone sneezes then we would have a Pavlovian thing going on.


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How does someone decide from what direction to approach the twelve-Nidānas?
From what I can gather (from wikipedia) there are four methods:

The Twelve Nidānas are explained in detail in the Visuddhimagga of Buddhaghosa, the central text of the Mahāvihāra commentarial tradition. Buddhaghosa recounts four methods to interpret the Twelve Nidanas:

Working from "bottom to top",
Working from the "middle to the top",
Working from "top to bottom",
Working from the "middle to the source".

The first method begins with ignorance and proceeds to sickness, old age, and death. The second method begins with attachment and proceeds to birth. The third method begins with birth and proceeds back to ignorance. The fourth method begins with attachment and proceeds to ignorance.

Given these different approaches, how can an individual decide which they are most suited to follow in order to revert the chain and where in the suttas can each approach be found?

I guess, you should follow exactly like stated in the suttas, because phrasing is important.

I had to look up what this meant. My understanding was that they went round and round. But I see you are just talking about different starting points. Is it possible to request a clarification in the question? I know the formulation is traditional but I wasn't aware

Because I believe I understand twelve nidanas, I suggest you approach them from the bottom up.
This way, each next nidana up will be the "cause" (or, more precisely, the ground or the context) for the one below it.
As I said here, I believe the relationship between nidanas is that of implication. Be sure to check out the thoughts of Nanavira Thera and ven. Buddhadasa for useful hints. I do not agree with all of their conclusions but they are on the right path, as far as I can see.


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Buddhas of The Ten Directions
What are the Buddhas of the ten directions?  What are the applications of this teaching in the Buddhist traditions?

Firstly, what are the 10 directions:

"Specifically, the ten directions are the eight directions of the
  compass—north, south, east, west, northwest, northeast, southeast, and
  southwest—plus up and down."

ref: http://www.sgilibrary.org/search_dict.php?id=2245
Second, sutras that attempt to list and describe the 10 buddhas.
http://www.tientai.net/teachings/dharma/buddha/10directions.htm
The traditional cosmology imagined that there could only be one Buddha in the world at a time. By imagining more universes, there could be more than one Buddha.
I think the particular phrase is one of the rhetorical flourishes you see a lot of in Mahayana-- it's a nice way to say all the Buddha's, everywhere.  The various names of the realms and 10 Buddhas mentioned in the Dasabhumika (realms like "Without Distress" or "Skillfulness") and Buddha's name "Virtue of Goodness" and "Practicing the 3 vehicles" are reminders of what the goals of Buddhism are and what is worth emulating.

The notion of Buddhas of the 10 directions is used to depict the first Jewel - Buddha - in some refuge trees. (In the picture below on the left one can see a circle of 10 Buddhas) Some refuge trees instead of 10 might have 3 Buddhas which in turn will depict Buddhas of the three times - Past, Present and Future.
Taken together, one can come across a phrase 'Buddhas of three times and ten directions' which will signify that the Buddhahood potential encompasses the whole spacetime we reside in. Wherever you go in space or in time, there is always a Buddha you can take refuge in.

Thanks for the answer.  However, I never heard of a refuge tree.  Would you be able to elaborate on that for a noobie,please?  Thanks again and nice picture... :)

A question around the nature and use of refuge trees would be a great second question ^_^


text:
What is the meaning behind different robe colors?
I have seen the same monk in two different color robes and am wondering why. They were dark red and of course orange. Ihave also seen brown, but that was zen, and if any other colors have relevance i would like to hear about them as well. I practice Theravada if that helps with referencing or relevance issues.

I believe initially the robes were mostly yellow as this was a color of renunciation in the locality at the Buddha's time. As the Dhamma-Vinaya spread the different robe colors occurred due to the local dyes monastics used in their respective localities being different shades and colors.
I do know that in the Theravada tradition at least in Thailand and Sri Lanka there is a differentiation in colors between forest monks and city monks.
This may be helpful : http://www.buddhanet.net/e-learning/buddhistworld/robe_txt.htm
The robe dye is allowed to be obtained from six kinds of substances: roots and tubers, plants, bark, leaves, flowers and fruits. They should be boiled in water for a long time to get the dun dye. Saffron and ochre (from the jackfruit's heartwood) are the most prevalent colours today. Though there is a tendency amongst forest monks to wear ochre and city monks to wear saffron, but this is not always the rule.

I've seen many Sri Lankan Theravada monks to wear Saffron and Tibetan monks to wear saffron or yellow and maroon.

With the historical significance of the color of the original robes explained by other posters, I'll just add a color chart to identify what regions different colors are mostly associated with today; keeping in mind there are exceptions:
Spice colored robes (shades of curry, cumin, paprika, saffron) - Southeast Asia
Bright yellow - China
Black, brown, gray - Japan & Korea
Maroon - Tibet region and diaspora
White or pink - Theravada women wherever they may be located; although it is noted fully ordained Theravada nuns are rare.
There are some differences in style as well; more detail at source:
http://buddhism.about.com/od/thefirstbuddhists/a/robes.htm

What are shades of curry? What is curry? This: http://cdn.sailusfood.com/wp-content/uploads/2006/06/spicy_chicken_masala_curry.JPG?

Curry, cumin, and paprika are typical household spices. Saffron is as well although it's more expensive. Curry is yellow, cumin is brownish, paprika is red, saffron is yellow.

Let me revise saffron, it ranges from yellow to orange colored. :)

Is this due to availability of dyes or for historical reasons or does it signify different spiritual meaning?

From my research it looks like the reason that original kasayas (stitched robes, made from leftover pieces of fabric and clothes found on trash piles, taken off corpses etc. - basically the discards of civilization) were ochre or brown-red, is because they were washed with red clay, used as a cleaning agent.
Ochre was the most available color of clay around the area Buddha lived and practiced at.
From this, we can extrapolate and assume that different colors originally derive from different types of clay available in whichever region Buddhism spread to. Later, the colors were standardized by schools and various different dyes were employed beside clay.

Tibetan lineages wear the maroon color of the cloak out during a Puja, and the yellow out if at giving a teaching.

Oh, In vinaya (code of conduct in monastery) Buddha allowed many types of die to be used for the robe.  Bark from different kinds of tree, or even red color from clay.  so naturally, there would be different shades.   Bark from Jack fruit tree produces brownish color where red clay (like what Andrei said above) produces reddish color.

The command was the color Kasava--that means dirty or stained brown. No other color allowed. But the patches and dyes varied, so the Buddha approved the MINOR variations of brown. The idea behind the color is that this is the color of mourning. The entire tricivara is based on ancient Hindu widow's weeds. No one ever answers THIS question correctly. Clerics today should all be wearing a uniform Brown, rather dark brown, end of story.

+1, dirty = the color of clay - from ochre, to brown-red, to maroon, to gray

of all the responses here, i am only surprised that Theravadan women wear white.  my experience is in Nyo Ho E (authentic Dharma clothing) as provided for in Japan especially through the teaching lines of Kodo Sawaki-roshi at Antaiji and brought to North America by trainees through there including Yoshida-roshi and Joshin-sama to Tomoe Katagiri-sama and Blanche Hartman-roshi.  white seems unusual because it is a basic, or primary color (as would be blue, yellow, red, and black).  but there are black robes for training priests in Japan (though the color is supposed to be "off" somehow).  by the same reasoning, i guess i should be surprised that yellow is mentioned a lot, but i am very used to seeing it.  it may be that the "yellow" is "off" somehow.  i think it should basically be modest, and what looks modest has a cultural factor too.  black is modest in Japan.  i think grey is worker / modest in Korea.  maybe in the US, it should be clothes from Walmart ... i don't think that's gonna happen but, that's my sense of the feeling.  very ordinary.

White is not actually a robe color.  Theravadan householders are described by the Buddha in the Tipitika as wearing white.

" Bright yellow - China
Black, brown, gray - Japan & Korea "

I want to add this trivia. The original colour of monastic robe in China was black or gray much like its brethen in Japan and Korea from the Dharmaguptaka lineage.
https://en.wikipedia.org/wiki/Dharmaguptaka
However Master Hsing Yun the famous Chinese monk from Fo Guang Shan in Taiwan found that the gambling obsessed Hong Kongers associated the colour black with death and hence was considered unlucky and did not welcome him. So for public appearances he wears the 'golden' yellow robe along with a bright red kasaya, as a form of skillful means. Taking this precedence Chinese monks begin to wear bright yellow robes.
Further more based on my association with the temple and brief experience as a short term novice monk I observed the following:

Within the monastic compound Chinese monks wear bluish gray tunic and
trousers inside for cooking, cleaning, meditation and to sleep.
For ceremonies and public appearances a black robe called the Haiqing is generally worn,
with a dark maroon Kasaya.
During public ceremonies only the ceremony conductor wear the yellow robe
and red Kasaya.
A brown cassock maybe worn for travelling.
You must take off the robes before you go to the bathroom, going in with only the gray inner wear

Originally, in the first years or so of the sangha, monks would make their own robes from scraps of cloth they found in the trash or in cemeteries, etc.  They would color them by rubbing them with dirt or clay.  After that, any earthy color, found in dying leaves of trees, such as red, yellow, brown, orange or maroon, was acceptable.  Within the Theravada, there's no hard significance between the different colors and shades of colors in this spectrum.  However, you will often find that all of the monks in one temple tend to have the same color and shade.  This is often not 100%, because they accept their robes from dayakas (donors) and they would not reject a robe because it was a different shade.  Similarly, a monk might have brought his robe with him from another temple.
I did see one temple, however, where the head monk had yellow robes, and all of the others had orange robes.  But this was just their practice, and is not from instruction of the Buddha.

Since I'm visiting a Buddhist temple here in Chiang Mai I thought that I would answer.  Brown robes can eat only once per day, orange/saffron robes eat twice a day and the maroon (Myanmar) robes can eat whenever they want. That's the word among the monks (they take eating very seriously).

Crab, I appreciate your comment, but I don't think what they told you is quite correct.  It may be the practice at their temple, though.  Thailand and Burma follow Theravada Buddhism, and thus they follow the Vinaya, and there's no rule like that in the Vinaya.  All Theravadin monks are allowed to eat twice a day, but the Buddha encouraged them to eat only once a day.  But that has no effect on the color of their robes.  Though again, an individual temple may differ.

Why do Buddhist monks wear orange?
Note: Buddhists also wear red or yellow, depending on different regions, like Tibetan Buddhists wear red, Chinese Buddhists wear yellow(not sure) etc.
Answer: Because Hindu ascetics(Yogis/Sannyasis) used to wear orange. Buddhism came out of Hinduism/Vedantic traditions(which are atleast half a millennium older than Buddhism) and thus its impact on Buddhism is clearly visible. There is much more common between these two spiritual traditions(Buddha himself was from this religion and never spoke ill of it, nor tried to bring radical changes in it. Much of Buddhist philosophy already existed before Buddha as Sankhya and Yoga schools of Hinduism. One of the Gurus of Buddha(Alāra Kalāma) was from Sankhya school of Hinduism. Sankhya & Yoga are atleast 95% similar to Buddhism, thus many things are common.)
So, now, why did Hindu monks start the practice of wearing orange robes?
Short answer:- Because orange/saffron (or red or yellow) is the color of fire, which is pure.Long answer:-This Indian tradition dates back to Vedic period. Vedas are oldest Hindu scriptures. Early parts of Vedas deal with rituals, society & ethics, while later parts, called Vedanta(core texts of Hinduism) deals with philosophy, spirituality, monastic life, yoga & meditation. Vedantic texts mention symbolism behind wearing of orange robes(which is related to early Hindu rituals). Buddhism just accepted/adopted/continued this tradition.It was Indian tradition at that time, which had origins in Hindu Vedas. So every Hindu Sannyasi/Yogi wears orange/saffron robes. The oldest Hindu rituals were offerings(sacrifices of grains, milk, butter etc.) into fire. Therefore, fire symbolised sacrifice. Since color of fire is orange(or red or yellow), the color also represented sacrifice(of our sensuary/material pleasures). Even today, saffron/orange, and also red and yellow are considered sacred in India by Hindus and used by Indian Yogis.This Vedic/Vedantic(Hindu) idea of monasticism is based on symbolic interpretations of early Vedic fire rituals(called Yajnas), the body of a Yogi monk symbolises altar of yajna, his conciousness is the fire into which he/she sacrifices(burns) his material desires, animal instincts and ‘sad-ripu’(six enemies- attachment to word, lust, anger, ego, greed & jealousy), his Prana (life force/Qi) is the sacrificer & the act is done by meditation. This metaphor for Yoga is discussed in the oldest & most important Vedantic/Hindu texts like Brihadaranyaka Upanishad section 2.2, Chandogya Upanishad, Kaushitaki Upanishad sections 1.4 and 2.1–2.5, Prasna Upanishad chapter 2 and many other later texts. In fact, there is a whole Upanishad which deals specifically with this topic only, i.e. , Pranagnihotra Upanishad. Therefore, the spiritual significance of orange robes is that it reminds the monk that he has to sacrifice his sensory/material pleasures, and that his body is like the sacred sacrificial fire of Agnihotra/Yajna for this purpose, and thus a monk is as pure as fire, which purifies everything and gives light/knowledge to everyone.
Conclusion: Buddhists wear saffron/orange robes because it was an older Hindu tradition which they appreciated/adopted. Thus, the symbolism(orange=ritual sacrificial fire) behind this is absent in Buddhist texts(correct me if I'm wrong), but is discussed in detail in Hindu texts. Most Buddhists don't even realise this meaning because most Buddists are outside India and they don't study Buddhism with proper Indian cotexts and are unaware that Buddhism was and is, more or less, a part of Hinduism.

The Theravada Bhikkhunis in California and the rest of the United States wear medium brown robes with ever so subtle hint of yellow/orange.
A Bhikkhuni is a female monastic in the Theravada tradition and there numbers are growing.The first year a lay person can try out the robes and wears white and is called an Anagarika.

Colors: https://m.youtube.com/watch?v=LI8Zx_QvNVU
The meaning of use of different colors is expression of own identification, no-unity, pride. That being the readon, like here, the Buddha allowed certain colors and forbid others. Yet desire for identification is like Dhamma timesless, and so the show goes on. There is a simile of a donkey wishing to be part of a heard of cows, thinking he's one of them: "Even their robes are different...", but of course such isn't, if one is badly informed, or bond to own-taken tradition, not the last measure.
What ever lies in the spectrum of saffron, dirty yellow, brown, not shiny orange... might be fine. Shiny is improper, as a monk would need to "destroy color", red is improper, dark is improper, green, blue... not to speak of white and gray, are improper, as well as rose.
[Note that this isn't given for stacks, exchange, other world-binding trade and use, but for an escape from this bond]

The Buddhist Vinaya code calls for monks robe to be if "discarded colour" or "spoilt colour" i.e. colours not of distinct recognition such as red, blue etc. During Buddha's time, robes are initially made from unwanted clothes collected and sewn and dyed wth tree barks, which turned them into dirty brown, even purplish or mud orange.
As time passes, the robes offered in different regions are commercially made using the available dye/tree bark in that region. And while it helps to identify where the monks hail from such as Sri Lanka, Thai, Myanmar etc. Hence, you find  each with a tinge of tonal difference. No big deal about the colour difference.
However for the Mahayanese Sanghas as those from China, Taiwan, Japan & Korea, Vietnam etc. you'll need some historical knowledge on how Buddhism travelled and when. In ancient China before Song dynasty, monks wore dirty coloured robes, purplish orange, using a colour mixed from leftover dyes. However during the Song Dynasty, the emperor took refuge in the triple gems and appointed his master as National Master (or Advisor). Historically yellow was recognised in China as royal colour, that only royal members are allowed to use. Since Sangha members are being recognised as the teachers of the Emperors and royals, they are therefore accorded the right to adorn in yellow robes. And the emperor insisted that his master and all sangha be accorded the royal rights with him offering the yellow robes to all monks in his country, and decree that all ministers and countrymen/women pay due respects to monks as they do to the royalties. While training in temples, samaneras wore white, after pabajja ordination, the trainees or novices are allowed to wear the grey coloured  罗汉服luohan fu (arahant clothing) as their daily wear (1 of the 3 robes) as they worked towards their spiritual development. As temples then were usually built high up in the mountains where water are shortage, washing becomes restrictive. grey being the discarded color and not so easily dirtied as white, it became the basic anenities of a practising hermit/monks esp. in Chan/Zen that was prevalent. Only when one had completed the higher ordination of upasampada, can one then be accorded the yellow robes befitting a master.
It has to be noted that in ancient China, temples (寺) are recognised as equivalent to  Minstry of Education and the abbot of temples accorded a rank same as a full Minister, approved only by the Emperor himself. So for monks in yellow robes, representing royal patronage, even Ministers or Generals had to pay their respect first and not other way round as if in audience with the Emperor himself.
Korean & Japanese scholars had started learning from China during the great Tang Dynasty, the traditional Japanese culture are mostly adapted from the Tang Dynasty, including its kimono, kanji, busdhism etc. While Korea adopted mostly from Song & Ming Dynasty of China.
However, in terms of Buddhist practises, both Japan & Korean follows exactly the same tradition as practised in their lineage in China , eg. Tiantai (Tendai), Chan (Zen), or Pureland perhaps with very limited alerations thru times.


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Is there any extreme of physical pain that a fully enlightened person would find unpleasant on any level?
In other words, by not conceptualizing sensations of physical pain, do fully enlightened people still experience unpleasantness and simply not label it as such, or is the experience fundamentally without anything that an unenlightened mind would label as unpleasant, so that the degree of pain becomes like pitch in music?

It's said that enlightened person feels single pain (only physical), while not enlightened feels two pains (physical with mental pain).
SN 36.6, Sallatha Sutta:

The discerning person, learned, doesn't sense a (mental) feeling of
  pleasure or pain: This is the difference in skillfulness between the
  sage & the person run-of-the-mill.

An enlightened person feels the sensation corresponding to pain, but it does not feel as pain, rather as pure (informational) sensation.
My teacher taught me an exercise thanks to which I had this experience first-hand. It is called kuem chok in Korean (I'm probably misspelling it badly).
kuem chok is performed by taking one of especially designed postures, "eagle posture" or "sleeping tiger" and others, which are inconvenient enough to generate bodily pain, but simple enough to maintain for a long time. The idea is to "go through" pain by exercising willpower, by not succumbing to the feeling of self-pity, until the experience of pain toggles and becomes something else.
After I was holding my posture for about 15 minutes, and had all my body shaking with pain, the sensation toggled, and instead of pain I felt heat and lightness. I could effortlessly maintain the posture and was surprised it felt difficult to me in the beginning.
This only happened once, and now the teacher moved on to a more difficult posture, "sleeping tiger", with which I was not able to switch yet. Needless to say, if I were you I would not try this at home without a guidance from qualified teacher, otherwise you may hurt yourself.

I am not referencing any suttas for this answer, it comes from my own experiences (I am not an arahat).
One who has obtained nirvana can choose whether or not to experience pain and can choose the level of suffering that is associated with that pleasure or pain. Having obtained nirvana an individual has the ability to reside beyond pleasure and pain and it also gives them complete understanding of pleasure and pain and things can not be understood without being experienced.
After some research, Sakalika Sutta: The Stone Sliver talks about how buddha cut his foot and endured the physical pain.

Excruciating were the bodily feelings that developed within him — painful, fierce, sharp, wracking, repellent, disagreeable — but he endured them mindful, alert, & unperturbed.

Although an Arahat would not have any mental pain arising with physical pain, that doesn't mean that everything would be just fine. Arahats could still find it burdensome, for example, in that it is constantly pulling on their attention and they wouldn't be able to do much as a result, so pain could still be quite debilitating in that the Arahat wouldn't be able to function by teaching, traveling, or other such things.

Of course enlightened people experience pain!  Even the Buddha did.  For example, in the Maha-parinibbbana Sutta, it is said of the Buddha:

When he had eaten Cunda's food, I heard,
  With fortitude the deadly pains he bore.
  From the sukara-maddava a sore
  And dreadful sickness came upon the Lord.
  But nature's pangs he endured. "Come, let us go
  To Kusinara," was his dauntless word.

There is some evidence (and the exact source is escaping me now) that he was only free of physical discomfort when he entered into the base of cessation (i.e. nirodhasamāpatti).  The Buddha even had to deal with a bad back on occasion (as in MN 53).
Of course, the experience of physical pain in not equal to the suffering of physical pain.  While techniques do exist to deal with physical discomfort, only enlightenment liberates you from the anguish it causes.


text:
How do the stages of insight before stream entry relate to the suttas
Are the stages of knowledge before stream entry mentioned in the suttas? How does this correlate with the Visuddhimagga? E.g. sabba-kaya-patisamvedi (in some interpretations) may directly relate to bhanga-ñāṇa.

The sixteen stages of knowledge are taken for the most part from the Patisambhidamagga, a treatise attributed to Sariputta. They are also enumerated in the Abhidhammatthasangaha. Some are specifically mentioned in the suttas, e.g.:
udayabbaya

Yo ca vassasataṃ jīve apassaṃ udayabbayaṃ
Ekāhaṃ jīvitaṃ seyyo passato udayabbayaṃ.
Dhp. 113

nibbida

Sabbe saṅkhārā aniccā'ti yadā paññāya passati
Atha nibbindati dukkhe esa maggo visuddhiyā.
Dhp. 277

ādīnava

Disvā ādīnavaṃ loke ñatvā dhammaṃ nirūpadhiṃ,
Ariyo na ramatī pāpe pāpe na ramatī suci.
Ud. 5.6

The knowledges are also closely related to the seven visuddhis from the Rathavinita Sutta (MN 24), again attributed to Sariputta (and Punna Mantaniputta).

Into the Stream is A Study Guide on the First Stage of Awakening by Thanissaro Bhikkhu
The contents include:

The Way to Stream Entry

Introduction

The practices leading to stream entry are encapsulated in four factors:

Association with people of integrity is a factor for stream-entry.
Listening to the true Dhamma is a factor for stream-entry.
Appropriate attention is a factor for stream-entry.
Practice in accordance with the Dhamma is a factor for stream-entry.

Association with People of Integrity

As he was seated to one side, Ven. Ananda said to the Blessed One, "This is half of the holy life, lord: having admirable people as friends, companions, & colleagues."
"Don't say that, Ananda. Don't say that. Having admirable people as friends, companions, & colleagues is actually the whole of the holy life. When a monk has admirable people as friends, companions, & colleagues, he can be expected to develop & pursue the noble eightfold path.

Listening to the True Dhamma

"There are these five rewards in listening to the Dhamma. Which five?
"[1] One hears what one has not heard before. [2] One clarifies what one has heard before. [3] One gets rid of doubt. [4] One's views are made straight. [5] One's mind grows serene.
"These are the five rewards in listening to the Dhamma."

Appropriate Attention

With regard to internal factors, I don't envision any other single factor like appropriate attention as doing so much for a monk in training, who has not attained the goal but remains intent on the unsurpassed safety from bondage. A monk who attends appropriately abandons what is unskillful and develops what is skillful.

Practice in Accordance with the Dhamma

this is what accords with the Dhamma: that he keep cultivating disenchantment with regard to form, that he keep cultivating disenchantment with regard to feeling, that he keep cultivating disenchantment with regard to perception, that he keep cultivating disenchantment with regard to fabrications, that he keep cultivating disenchantment with regard to consciousness. As he keeps cultivating disenchantment with regard to form... feeling... perception... fabrications... consciousness, he comprehends form... feeling... perception... fabrications... consciousness. As he comprehends form... feeling... perception... fabrications... consciousness, he is totally released from form... feeling... perception... fabrications... consciousness. He is totally released from sorrows, lamentations, pains, distresses, & despairs. He is totally released, I tell you, from suffering & stress."

Stream Entry & Its Results

Introduction
The Arising of the Dhamma Eye
The Three Fetters
The Character of a Stream-enterer
Rewards
Advice

If you look at the study guide Thanissaro Bhikkhu links each sutta.

Good answer but tangential to the relationship between Vidarshana Nana as per Vissudimagga and the Suttas. Up voted but not accepting it.