Hi there,
I was in Seoul in early January this year. I stayed in this little hostel called Korea Hostel (
http://www.hostelkorea.com ). Cost me approx S$30 (W30,000) per night for a single room with bathroom. The floors are heated during the cold winter. Room is small but sufficient for you to lay open your suitcase luggage for packing. Wifi connection is free in the hostel. However, in the room i stayed the toilet does not come with a basin. The location of this hostel is not that far from the MRT (about 8-10min walk from the surface exit of the MRT station). The bus stop that serves the airport bound bus is about 5minutes walk from the hostel and it accepts the Seoul stored value MRT ticket or tourist stored value MRT ticket.
Language is a barrier in Korea. Do try to use your mobile to take the food which you want to eat together with the korean words beside it before you go Korea. Photos of cow, pig, chicken, rice, noodle, udon, bread, international toilet symbol, etc will be nice to have too. Atleast you do not need to act it out to show the waiters what you want to eat.
You can easily find many Chinese national ladies working in shops such as Faceshop and other cosmetics house. They speak chinese and Korean. If you speak chinese, you might be able to ask them for help and local information too.
Transportation in Seoul is cheap. I took the MRT out and walk my way back (excess of 10-15KM per day) to the hostel most of the nights. Very interestingly, their wholesale markets are open from 11pm to early morning.
If you need a guidebook for Seoul (latest 2010 edition but in traditional chinese characters as I bought it in Hong Kong late last year), I could lend it to you.