I want to start a grow room for vegetables, I have a room that I want to use for flowering them, size 5ft by 8ft, I was thinking a 600 watt? With what size can fan? I only think I can get 20 vegetables in the room at a time to flower? Also my friend will be doing the vegging in a hydro tent using a T-5 light, does that sound right? And I am thinking all soil.
You definitely have the right idea. The optimum light spread for a 600w is 3×3 to a 4×4(for heavy flowering/fruiting plants. You can get a much larger light spread with leafy plants like lettuce, basil, etc). A digital ballast will give you more light for the same watt, so you can get the maximun light spread. The fan has many options. If all you want to do is cool the bulb and take the hot air out of the room a standard 6″ can fan will be your best bet. If you think you might want to expand on your lights then you might want to get the high output 6″ can fan.
Also if you are going to run a charcoal filter then cut down the cfm of the fan. The high output would be best in that case. For the veg I like t-5′s. They are easier to keep cool and still preform awsome. I try to have an area thats close to 1/2 the size of actual plant square footage. The more room to work the better and easier! I hope this will help you out.