WHICH VISA APPLICATION FORM TO FILL OUT FOR CHINA AND HONG KONG TOURIST VISA, AND WHERE TO SUBMIT APPLICATION.

Canadian passport holders are allowed to stay in hong kong for up to 90 days without a visa for the purpose of leisure visit. So you don't need to apply for a hong Kong visa if your passport is still valid for one month when you leave Hong Kong.

Since you are on a tourist visa in Thailand, I'm not sure if you can apply for a China visa there successfully or not. But you may try. You are also allowed to apply for a China visa in hong kong. So you can also try in HK if fail in Thailand.

Requirements for a Canadian citizen to apply for a China tourism visa:
1. An original copy of passport with enough blank visa pages, valid for at least another 6 months.
2. Fully completed copy of Visa Application Forms (Form V2011A and Form V2011B) signed by the actual applicant
3. One recent 2×2(in.)-sized color passport photo
4. Under some situations, the original and copy of Chinese Hotel Booking and Return Air Ticket are required
5. other deemed necessary requirements by the embassy