I don't think there is a big gap between Chinese GAAP and US GAAP. Basics are essentially the same. The accounting theory and practice that you are going to learn in your Master program are basically similar to what you have learned in China. No major differences. You could only tell the difference if you are encountered with some specific issues, like Goodwill, fair market value evaluation, etc.
However, US GAAP&FASB rules are way more complicated than Chinese GAAP. Well, you are not going to learn too much FASB stuff in school. So, don't worry about that.
Since all major countries are going to start adopting IFRS in the next few years, I believe, the courses in the master program are going to be updated, covering the differences between IFRS and FASB.
Well, tax is another story. US Tax is VERY VERY complicated.
In terms of the job market in China, I have no idea.