Just slide them under.
Might not be the best for the polished pistons to be out in the open for an entire winter storage. Stands to hold it and the lift collapsed would be better.
I sat in the car with it fully raised. As long as you are on level ground and know how to properly set a lift you are good to go. I wouldn't have a second thought about a trans./clutch/flywheel swap with this lift. BendPak is a well known and long lived maker of automotive lift systems.