1. A dozen small ones should cover you. Don't think brand really matters much.
2. 15-20 lbs. is a good starting point. If getting it is a hassle, get more, it sucks to run out.
3. Probably not, but I usually set up a box fan to move the air around some.
4. 1/2 inch is good, you can stack it if you need a thicker section.
5. Won't help I think.
6.
ABSOLUTELY NOT, if you bug, the board will idle at a bios post code, just let it warm back up idling. You should break it down while everything is frozen otherwise you'll have frost melting and running places you don't want it.
Neoprene and armaflex nsulation I bought from:
http://kingpincooling.com/
Kneaded eraser I bought locally from Hobby Lobby.
Acetone, I bought from Home Depot