You've answered your own question. Peter himself was wondering what the dream meant and he went on to explain it to his fellow disciples. The Jews felt that the gentiles and samarians were unclean due in part to their uncircumcised state. But God clearly showed him in the dream that all animals and in this case peoples were equal before God therefore they were just as deserving of the message of salvation as the Jews. The verses that talk about eating all kinds of animals are found in 1 Timothy 4 :
1 Timothy 4
Instructions to Timothy
1The Spirit clearly says that in later times some will abandon the faith and follow deceiving spirits and things taught by demons. 2Such teachings come through hypocritical liars, whose consciences have been seared as with a hot iron. 3They forbid people to marry and order them to abstain from certain foods, which God created to be received with thanksgiving by those who believe and who know the truth. 4For everything God created is good, and nothing is to be rejected if it is received with thanksgiving, 5because it is consecrated by the word of God and prayer.
Its clear enough for me without a bible commentary I hope its clear enough for you.