"Swine" is very rarely used by Americans, even as an insult. We prefer to use the word "pig" instead.

Although I am not native speaker but I agree with mike1988. This word was borrowed from German "Schweine". By the way, I heard that some people in Germany call other people such word. Try to guess who "other people" are ;-).

This is an old fashioned term, rarely used nowadays.

I am British, but I have only ever heard this word used on the TV and in books and not by real people. So no I don't think it is commonly used.

Swine is a bit more British, used by the middle and upper middle class.