Visa: http://www.koreaembassyusa.org/
Airport: Incheon/Seoul International Airport
Airlines: Korean air (with Delta), Asiana (with United),
Singapore air (only from San Francisco)
Tour: http://english.tour2korea.com/index.asp
http://www.airport.kr:80/notice/NoticeList.iia?
functioncode=49&fake=1231541804628
Cell phone: you can rent a cell phone from the airport. (renting will cost
less than roaming US phones)