안녕하세요 마리사!
한국에 관심이 많은가봐요?
= You are very interested in Korea, aren't you? / I guess you are very interested in Korea, right?
미국인 맞으시죠?
= You are american, aren't you?
초등학생 처럼 이라도 무지 잘하시는걸요??^^
= You are very good although it is like an elementary school student level.
Hope it helps.