Food is generally healthy there unless you decide to do the KFC thing (yes, you get pizza hut (which oddly enough tastes better there) and all the western franchises. You can eat in native places and there the food (I’m a vegetarian) was healthy and tasty (but I like Chineese food.).
There are a number of cultural mores to follow that would help you fit in better. Those links that wigmore gave you is a good start here are a few more I learnt in my visit there:

Never leave your chop sticks (or fork) in the food / rice in particular when eating. You usually get a stand that you can rest your chopsticks on. It considered an insult or has something to do with death (I don’t remember the reason but it was important to my chineese host).

When giving something to someone give with both hands (this rule applies to something as small as a bussiness card too).

Good luck on your trip I wish I was going to China :) .