I have 10 CFLs in my rubbermaid box at the moment, 6 26watt and 4 42 watters. I plan on adding another 6 or so bulbs as they get bigger.
For ventilation I bought a bathroom fan for 15 bucks, cut a hole in the top of my box and laid the fan on it....then i plugged it in. cut a couple holes near the bottom for intake. pretty simple. A pc fan is the same principle you will just need to cut the right sized hole so the fan sits flush with the box and sucks air out. It ain't rocket science.