When using chopsticks, avoid holding them in a way that points your index or middle finger at somebody.
During their free time, the most Chinese enjoy playing Mahjong.
Greetings occur with a nod and smile.
In conversation, do not be too animated and avoid using hand gestures.
During mealtime, slurping and belching are acceptable as it shows that you are enjoying your meal. Never take the last bit of anything unless the host offers it to you.
Gift-giving is prominent but also very precise. They are always presented with two hands. Acceptable gifts include anything from your country, and unacceptable gifts include flowers (which are common in funerals), clocks, or anything sharp. Gifts should never be wrapped in black, blue, or white.
During business negotiations, understand that the Chinese have a very difficult time saying no, and that mobile phones will constantly be ringing. In addition, never show them that you are anxious, upset, or impatient.

https://www.cia.gov/library/publications/the-world-factbook/geos/ch.html (Majority of information)
http://www.stats.gov.cn/english/Statisticaldata/CensusData/rkpc2010/indexch.htm (Ethnicity and city population data)
Wolfram|Alpha (Currency exchange data)
Information accurate to best of ability as of 30 October 2016