If I get the unlock code from tmobile, and unlock my phone, and then go to China, and buy a data plan (from a carrier in China).... will my 8320 work??
Try to pick a carrier in China before you go. There are a number of members from Hong Kong on Crackberry and maybe they can offer some insight.
My son was in Hong Kong earlier this year and in Shanghai last year and he said that his Swisscom (Windows Mobile, yeah, I know) phone worked perfectly in both places and he was able to access the internet with no problem. Of course a BlackBerry data plan is a very different proposition so do your homework before you board the plane would be my advise.