True. America used to be अमरीका (pronounced Amreeka) in Hindi. But in recent years, the spelling/pronunciation अमेरिका (which is closer to the English pronunciation) is gaining more popularity even in newspapers and the like.
No. The word से (se) means from. The word में (mēṃ) means in. Peter is from America means he is now somewhere else. He was probably born in America. Peter lives in America means that he is living in America now.