Laptops and base units will work fine in the garage. Just short of water dripping on it, most laptops run windows 7 and sleep when you close the cover. This in itself will keep condensation off of it while charging the battery releases heat. For practical purposes, Lay a plastic cover over it if...
I previously owned a Tri-Level. My hotwater pressure regulator flooded the carpet. (Insurance companies are a headache in regard to this. Don't throw away a failed pressure relief valve.)
If I were to do it again, I would put linoleum on the floor and throw rugs.
The most efficient way to heat is a heat pump. Since they are still pricy, you could get the mexican version. Answer: A small Air Conditioner installed backward into the chamber. Basement would retain heat but the room would concentrate it. In Minnesota, you probably want to keep the heat in the...