What kind of visa should I apply for?

A friend and I will be traveling through Asia (China, Thailand and Cambodia). We have booked our round trip ticket from Canada to Beijing. After two days after our arrival we will be flying to Bangkok. We will then be returning 4 weeks later to Guangzhou. We will then be going to Hong Kong for 2 days and returning to Guangzhou. We will be spending 3 weeks in cities between Guangzhou and Beijing until our return flight to Canada. We are both Canadian citizens. Do I require a double entry visa or cause of the visit to Hong Kong a multiple entry visa. Also the hotel/hostel booking of every night required?