i worked for AS programs for about 3 years. one job was quite good, one okay, one absolute, complete shit
1. you'll generally teach kids who don't want to be there, and many parents treat it as cheap babysitting. kids will be generally really disrespectful, and if you discipline them too much, they'll complaint to their mum and will leave the program, which you'll get in trouble for. kids know this, generally, so will piss about as much as they can. the main idea in AS programs is to have "fun". do not worry about teaching. complete the book quickly, play a game
2. depends. i'd start off with a strict no korean rule, which would generally taper off towards the end of the year, as i'd generally get sick of the bratty kids and terrible AS management by then
3. you'll probably have to write student evaluations every 2 or 3 months. a few sentences per student. i used a dictation program which sped things up x10.
4. you'll teach by yourself, and a korean teacher will teach by herself next door. every day you'll swap students. you'll never teach together, but you may have an assistant teacher in your class. generally, they are useless, and sit at the back on their phone the whole time. although they get paid minimum wage and probably don't give a ****, so i don't blame em
5. i will never, ever, ever work in an after school program again. christ. absolutely no way. i've never felt so unappreciated, never taught such awful kids. i would often not even be supplied with basics such as board markers or paper or even my own textbook. was often not paid on time, had to file with the MOEL to get my severance. please read your contract carefully. don't sign it there's ANYTHING you don't agree with. they will most likely try to screw you over at some point.
having said all this, the hours are decent and the pay is as well. the most annoying bit is moving to morning hours in summer/winter breaks, as it messes with your other jobs.
oh. have a look on facebook for these groups: "After School Jobs", and "After School Jobs You Can Trust". you can compare your offer for jobs posted there.