I spend a wonderful two years at Hwassan. Actually, I was sad to leave... but I got a university job, so just like you I had to "obviously" leave it. :)
Anyways... they give you a really good contract. Your co-teacher (Jeong-mi) is awesome, a really nice woman, she will let u take almost full control of the class if you feel comfortable with that. She's often busy with paperwork, so you'll end up teaching 85% of the class. The apartment I had there was small, but I believe they are going to get a nicer apartment for you. They provide all you'll need (fridge, bed, desk, etc.) and more.
Kids are awesome there. I really miss them the most... Not much discipline to do, but you can't be "nice" to them. Treat them like students and you're fine. As for living in Sanbon, it's great. Good crew of foreigners there (I'll introduce them to you if you'd like) and Sanbon has pretty much everything in the way of food & entertainment... As for getting into Seoul, it takes about 45 minutes to get to Hongdae, and maybe 50 to Itaewon. Depending on if you take the fast express bus from Dang Dong, getting to Gangnam is possible in 29 minutes (I timed it..haha).
So, Joy! Take the job! Hehe, that's my advice. I'm surprised they don't have a foreign teacher there yet. They having trouble finding someone? It's funny, cuz I gave them notice! hehe. Poor Jeong Mi was probably just too busy...
You'll love it there.
As spoken from a previous teacher who worked at my prospective new job.
Sounds pretty darn good.
Friday, I will get a look for myself when I have the interview.