1. Sorry, I'm not going to dig into product selection for you; I've done more than I said I would.

2. Use propane.

3. Electrical heat will be VERY expensive not matter how you do it. If you have a oil heat with a boiler . . . I don't know what the costs will be.

6. ONLY if there are no connections. Air doesn't get into wires; it does get into receptacles and switches.