As a photographer myself there are some essential items to take that occassionally get overlooked. First to pack has to be silica sachets, air conditioning and in and out of rooms will produce condensation and they help big time. Small screwdrivers, just a tiny cheap set for the 'what if' situation. Spares of everything, batteries,film or memory cards because there is every chance you will need them. On the subject of memory cards take more than 1 and change it in the canera regularly, so if you ever lose or damage 1 then you still get a good selection of images. Dont forget to format your memory cards too ( but then you knew that anyway). Consider a well padded and weatherproof case for your gear it is a good investment. Personnaly I use lowepro and swear by it, great protection AND a lifetime guarantee.
Enjoy your trip to China and if you see a big guy carrying a huge backpack full of too much photo gear looking worn out that will be me, smile and say hi!!