On the 400w question. I have a 400w digital ballast and "cool breeze" reflector. I set the ballast on a high shelf, and I have a thermometer mounted on the wall right above it and it's never gotten over 79 degrees.

All I've ever used is a small Vornado brand desk fan, lol. Blowing half through the reflector, half over the canopy it's worked perfectly. I could lay my hand right on the reflector and it's just warm. However I do have attic access in the closet ceiling which I've left half open which is allowing tons of warm air to rise out.

Also, those ballasts come with long cords. You could put it outside the room entirely if you absolutely had to.