I've spent most of the past 6 years odd working abroad, and mrl is pretty close to the mark, and covering most of the bases.
Our company works on the basis of overseas allowance of about 10%, plus a location premium based on a number of factors (language, safety etc) Australia wasn't seen as a hardship, so just the base 10%. Serbia was 25%, Brazil was 30% IIRC, Dubai was 15%, currently in India it works out to be about 40% ish. 40% sounds about right for a civilised part of China.
You also want either the company to provide you with an accountant for preparing your tax return, or an allowance for you to get one, can get a bit messy with overseas tax and equalised tax agreements etc.
Mobile phone certainly a must, I was stung once through things being a little vague on this front.
My contracts have always had a guarantee of at least 3 months work back in the UK after the assignment.
Make the most of your time, should be a fantastic experience. While it's nice to have the familiarity of an ex-pat club, get involved in things with locals to get a better idea of local life. It certainly gives you a different perspective on things when you return home!
Feel free to email me if you want any further info.
Cheers, Rich