Thank you for all of you guys above!

I have decided not to buy the flight pass this time. Searching a RT ticket YYZ-HKG seems a lot of work to me because I am still thinking whether or not have a few days stop at Vancouver in September.

For the upgrade certificates, I checked it out carefully and don't think I can use them since I am looking for low rates.

By the way, my senior told me it's not too bad taking Coach Canada from Kingston to Toronto International Airport. Basically I need to take the 1:30am bus and spend 4 hours on it. Well, good to know I can save the 55mins flight between Kingston and Toronto. The plane they used is the smallest I've ever taken - only 18 passengers. Last time they asked the ladies to board first and to fill in the last rows, because they got too many baggages at the back. I always feel funny when taking that little plane....