You cannot travel to China as a pax unless you have a scheduled flight assignment and a permission approval from the CAAC for your flight and you would need to show those official documents to the immigration officials upon entering China. As far as where to get a C visa, any Chinese consulate will issue them. They require a stamped company letter from your DFO and you must be on an approved list of Operators in order to get one. Also realize most are issued with only a 10 day maximum stay in China.