Ok. I guees you live somewhere, where there it is cool at night. Waterproof sheets would mean waking up in a pool in the morning here. :))

Fancy bedframes are overrated, but having a mattress on the floor is not great. It needs to breathe from the bottom. You can get or build a very cheap and functional frame, but i would advise against having your bed on the floor for a long time.

Because 7*20 minutes is more than 2 hours. :)