Chinese ogrinaztnion
As a US citizen you are supposed to report income from anywhere in the world to the IRS. Does not mean that you will be taxed however as people have different situations etc.
Working in China works for some. Things happen in slow motion especially as far as paper work goes. Everything else is "about" and subject to change at a nano second's notice so be very very very flexible. It's disorganized most everywhere but people are friendly.
Eventually you get used to it or you bail out.
If you walk off your Chinese job -do not finish your contract - you will probably never work in China again as you will need a release letter from your employer to get a subsequent work visa.
Good luck!