For my country of citizenship, I do need tourist visa for Canada. However, all I need to do (for the sake of arranging my immigration status in USA) is leave USA and come back, so I will not even leave the terminal area in Canada, just fly back the same day to make a fresh re-entry in USA. Will I need a Canadian visa for this? Is there anything to stop my flying out to Canada, provided I do not leave the terminal area?
It is possible to do a visa entry without flying (to Canada). For example, wherever there is a bridge to Canada (Detroit, Buffalo, etc) you can go partway across the bridge, turn around, and come back through US immigration.
The trouble you will have with a flight to Canada is the airline will want to be sure you have the right to enter Canada first (especially since you require a visa to enter Canada). Without a visa, you probably won't get on the plane.