There are essentially two types of teaching job in China. Working for a university, or working for a private language school. A university job will require a minimum of a Bachelors degree, and involve working with adults who have a reasonable grasp of English already and some of who may have very good English. These jobs are the most sought after, because they pay quite well and the conditions are generally quite good. You will be expected to teach around twenty to twenty five hours a week in most cases, but will probably do another ten to twenty hours of planning for those classes.
Working for a private language school will almost always involve teaching in a government run kindergarten, primary school, middle school, or a combination of all three, as well as evening and weekend classes teaching children and adults. In schools you will teach the same class many times, so there's less planning involved. The quality of schools varies wildly, and there are some real nightmares out there. Dave's efl cafe, amongst others, is a good place to find out from others what particular schools or agencies to avoid.
Teaching in Chinese schools is not like any other kind of EFL teaching your likely to encounter. Chinese kids are taught English by Chinese teachers. Foriegn teachers are there in many cases simply as live examples of how English should sound when spoken. You will often not be required, or even allowed, to teach grammar for instance. Some schools do not even require you to teach from the syllabus, as this is taken care of by the Chinese English teachers. They will be happy for you to teach the kids about your life as a foreigner, and if you can teach them a few Beatles songs as well it's a bonus. No, I'm not kidding. I suggest you have a look at www.middlekingdomlife.com
before you commit to teaching in China.
Be the change you want to see in the world.