I wouldn't recommend bringing the cat. Not if you actually liked it. Besides, it is very hard to get the cat back into your own country after it has been to China.
Mail works fine. Mail happily comes in using pinyin addresses, but they take longer than if written in characters. Mail seems often searched, but gets there eventually, sometimes in a few days (9 days was a minimum from Oz) sometimes very late (over 3 months - this was by air) and once didn't come at all.
Depending on where you are going, nearly everything can be obtained here, see the thread called something like 'what to bring'. Big clothes aren't impossible to find mostly (can be difficult at first, but then, lots of places will make what you want), but big shoes are. Things like that. Chocolate is available but not cocoa where I am but most of the chocolate is pretty ordinary. No chocolate with nuts.
You will find that books are the important item, unless you like reading ebooks from a computer. See the what to bring thread.
Just cross posted with ND. Yeah, what he said.