Travel Visa for Canadian living in the US

I live and work in the US (permanent Resident) and I am a Canadian with Canadian passport only. My upcoming trip is to visit China in Feb 2013.

I am traveling back to Vancouver to spend the Christmas holidays with family. Am I still eligible to get my tourist Visa in Vancouver while I am there or do I need to apply for it while in the US? I am just looking at the convenience since I am going to China with my sister - who lives in Vancouver...

Second, I have already booked my flight to Hong Kong and I have my hotel already booked in Kaiping because I am hoping to take a train/bus from Shenzen. Do I need any other documents when applying for it?