Cleansing of unclean meat to clean meat interpretation of Acts 10:17-18 and 22-23 in relation to Isaiah 66:17 I have never read in the bible whether eating of unclean meat as described in the Old Testament where it is allowed to eat "unclean meat" or unclean meat is now clean meat.

Except for one vision from Peter where the vision orders him to "eat unclean meat" however, this is clearly not literal as the context is for Peter to preach unto the Gentiles: 


  Acts 10:
  
  (17) While Peter was wondering about the meaning of the vision, the men
  sent by Cornelius found out where Simon’s house was and stopped at the
  gate.  (18) They called out, asking if Simon who was known as Peter was
  staying there.
  
  (22) The men replied, “We have come from Cornelius the centurion. He is
  a righteous and God-fearing man, who is respected by all the Jewish
  people. A holy angel told him to ask you to come to his house so that
  he could hear what you have to say.” (23) Then Peter invited the men
  into the house to be his guests.


Other verses in the bible tells "all foods are clean" however we should take note that it says nothing about "all meats are clean", food is totally different word from meat. 

Was the vision literal or not? If it's literal what is the biblical proof? Why are people lead into concluding that this vision is to be taken literally?

UPDATE:

And what could be it's relation to Isaiah 66:17 which states:


  Those who sanctify themselves and purify themselves, To go to the
  gardens After an idol in the midst, Eating swine’s flesh and the
  abomination and the mouse, Shall be consumed together,” says the LORD. (NKJV)


Which by deduction swine flesh as described in this verse refers to unclean meat, and the verse says, those who eat these Shall be consumed together which by deduction again means, AFAIK, refers to the end of the world. So in other words, those who consume unclean meat  shall perish together in the end of the world, which basically puts the interpretation of Acts 10:17-118, 22-23 in question:

"It's okay to eat unclean meat as interpreted in the vision but doing so will cause you perish in the end" -- a questionable argument. 

So I have two concrete questions here:


Was the vision literal or not? If it's literal what is the biblical proof? Why are people lead into concluding that this vision is to be taken literally?
Why are people lead into concluding that this vision is to be taken literally and eating unclean meat is okay as it is already clean when there is verse in Isaiah 66:17 which conflicts with the interpretation? 


Answers in the views of [protestantism] would be appreciated.
The vision was understood by Peter in a specified way as listed in Acts 10:27-29


  As Peter talked with him, he went inside and found many people
  gathered together. He said to them, “You know how unlawful it is for
  a Jew to associate with a foreigner or visit him. But God has shown me
  that I should not call any man impure or unclean. So when I was
  invited, I came without objection. I ask, then, why have you sent for
  me?”


And again in Acts 10:34, 35


  Then Peter began to speak: “I now truly understand that God does not
  show favoritism, but welcomes those from every nation who fear Him and
  do what is right.


Thus, the vision of the sheet was used by God to explain a very important lesson to Peter as observed by Ellicott in his comments on Acts 10:13


  in like manner, hungering and thirsting after a wider fellowship which
  should embrace "all manner" of the races that make up mankind, while,
  on the other hand, he was as yet waiting to be taught that the
  distinction between Jew and Gentile was done away in Christ.