Chief - I have a regular exhaust type fan air-cooling my hoods. It goes through my tent and lights and out the other side. I have a 200CFM fan hooked to my carbon filter and blowing out the 4" exhaust on top. You should upgrade your bulbs to the 430W
EYE Hortilux. They put off close to 10,000 more lumens each then a standard 400. so you would have like 20,000 more lumens with the extra 60 watts!
As far as cerventas goes I don't think the guy has grown a plant a day in his life. Some of the shit he says is off the mark. I don't wanna bash the guy, I mean he had a cool job to cruise around and check out grow ops and write articles about them, but that's about it. Anyone who has grown in the 70% humidity range can verify that photosynthesis doesn't stop and buds flourish in that enviroment. It is not the humidity that causes bud rot, or root rot but bacteria. As long as you keep your grow room clean from contamination and pests you will be ok. As far as the camera goes I don't think that I am gonna shell out a shit ton of money on a SLR quite yet. I have a lot to learn still, and am thinking about picking up a Fujifilm Coolpix S1000 to play around with. It has a lot of the capabilities of a digital SLR but is a point and shoot camera. I found one new online for like 150 bucks. I found out about it from a thread on here in the Photography forum. The camera rocks for the money.