sorry Ariel, some (not all) of your infos are wrong
pay depends on experience and wether or not u are typerated. for exemple, I got an offer at around 55000 chinese yuan (5500 Euros) (before tax) + 3200 for housing allowance (320 Euros)
base is Shenzhen, at least the expat suburb is quite nice and 30mn by boat from hongkong
for the rest, you are pretty much right, it's unstable !