There are a lot of people going to study in Korea these days! However, if you want to work and study half-time, it seems that you have to do it after 1 year, and you have to apply for a part-time work permit, anyway, you have to stay in school for a while for this kind of visa to work.
About all kinds of expenses, messy first to bring about 10W it (N years ago the annual price), of course, may be now a variety of policies down in Korea, and more exchanges with the domestic. That 80% will be much cheaper, but prices are still high, buy things on the word, expensive.
/