Travel from toronto to thailand with plane change in Guangzhou.

My wife and I are holidaying in Koh Samui, Thailand. We have valid Canadian passports and will only be in Guangzhou for 4 hours.
1. Do we need any kind of visa I.E 24 hour direct transit?
2. If so, how do we get them. i.e. before we leave Canada or when we land in Guangzhou?
3. We are travelling business class so we will be in the first class lounge while at the Guangzhou airport.