Visiting Philippines and while in Philippines - will do a trip to Great Wall of China -3 days

Hi there,
We are Canadian Citizens and will be visiting Philippines in June, we would like to visit the Great Wall of China and the Forbidden City in 3 days via Hongkong Beijing. Do we need to get a visitors visa before flying to HongKong? Can we avail a 3 day free transit? Or should we apply for Tourist L type in Cebu city? Please help.