@josh I prefer the KJV because "thee" and "thou" are known to be more intimate forms of "ye" and "you" and that distinction is important. Though it's much more lyrical than modern translations which are easier to understand.

The New Testament is the beginning of Christianity, but it makes zero sense without the context of the Old Testament, which is still a brilliant and entertaining read in its own right. Check out the book "The Bible as Literature" by Leland Ryken to get a better understanding of its literary forms, there's so much extra meaning just in the writing style alone.

I'm not Catholic so I don't know the third question.