Sorry, it took a couple of days to get back to ya! I had to celebrate a little over the weekend because I landed my first solid customer. The are a fab shop here in town that specialize in chasis and high end turbos, blowers and exaust systems. They were vey pleased with the first two parts I done for them and have committed all their biz to me including ceramic coatings. Things are looking up!!
Now for your questions:
You will be able to use a switch from a house oven but you need to consider what to use for a panel to mount it inside of.
for the fan & motor
http://www.mcmaster.com/ pg988 Shafts
http://www.mcmaster.com/ pg601 Small-Diameter Light Duty Fan Blades
http://www.mcmaster.com/ pg973 Pulleys
For the motor I would probably rob one from an old washer or something then get it to the needed speed with the pulleys. Use the pages above for reference only and you can also check out grainger.com for the same products.
For the vent maybe a 2-3" hole on the top with a flat steel damper that can be adjusted over the hole to control air flow.
Wiring you will need 6/3 gauge wire with ground from the breaker/ plug to the oven. The internal wiring will need to be a minimum of 10ga.
Jason
www.autocyclepc.com