Teaching ESL in South Korea?...advice needed?

[Enlightenme!]

Well, I got an offer to teach in a city called Yeoung Ju. I am wondering if anyone heard of this city and what it's like (not too many have up to this point). I confirmed with a former teacher of the school that it is a good school and the recruiter is excellent. I got two confirmations that the recruiter is good so far, I wish I had another confirmation about the school.

I would also like to know how flexible the new visa regulations are for US citizens.

Additionally, I'd like to know:

1. If I discover it is not a good school, how easily can I direct
my existing visa to a new employer, if at all?

2. What other jobs, if any, can foreigners pursue in Korea in
conjunction with teaching or besides it?

Thanks