Usage of 的 to refer to a generic class of things I'm wondering if this idea is correct: that 的 can generally be appended to and adjective in order to refer to the entire class of objects satisfying that adjective.

Example: 
好吃的 (delicious things); 我喜欢好吃的 (I like delicious things.)
漂亮的 (pretty things); 我喜欢漂亮的 (I like pretty things.)

What are the limitations of this idea, if it is even correct? How about 大的 (big things)? Can I say 我不喜欢大的 (I do not like big things.)? I guess that's a little vague more possibly, since 'delicious' (example above) obviously refers to food. I can imagine a casual conversation in English, where it would be appropriate to say "I like pretty things", and thus I'm wondering how people might say such things in Chinese, both formally and informally/casually/colloquially.

What if you told a friend to go purchase an item for you, and you wanted to colloquially say you don't want the "big one" (assuming the item has several size choices), could you say "不要大的", "不是大的", or just "不大的" or "不大"?

I'm most interested in what feels most natural to a native speaker. If I said either of the last four phrases above, would a native speaker know that I am stating a preference of not wanting the 'large size item'?
Short answer: yes. Your understanding is mostly correct.
Long answer: what happens in a sentence like


  我喜欢吃好吃的 
  I like to eat delicious things


is that you are omitting something that would otherwise appear after 的. In the example above I omitted 东西。
This omission is fine with very generic nouns. I can come up with the following:


东西 (material thing): 我喜欢吃好吃的[东西] I like to eat delicious [things]
事情 (immaterial thing): 我不喜欢复杂的[事情] I don't like complicated [matters/stuff]


You can then omit any other non-generic noun provided that what you are referring to is known from the context. 


  你回来的路上能帮我买一些苹果呢？我不要大的。
  Can you buy me some apples on your way back? I don't want the big ones.


If it is not easily understood from context, than you should specify the noun, as in: 


  我喜欢可爱的东西
  I like pretty things.


To make up a rule of thumb, just remember that you are omitting something. If you can convince yourself of this, it's easier to distinguish between noun phrases with an omitted noun and regular adjectives. 
In your examples above:


不要大的 -- noun phrase with omission -- I don't want the big one(s)
不是大的 -- adjective, with 是 for emphasis -- It's not big!
不大的 -- adjective with end-of-sentence 的 particle (expresses certainty) -- It's definitely not big!
不大 -- negated adjective -- not big


Therefore, the correct way to colloquially express the adjective + omitted noun is by preceding it with a verb, just as if it were a normal sentence.