kinda like this?

This is my friends hydro setup. He vegged for a week or two, then flowered. I think this is Power Plant from clones (40 clones). He didn't get much out of this, 400grams.

I looked at your drawing again, and I'm thinking about your height issues, but LST or SCROG is great for that... I got a SCROG going right now in my second grow, and it helps a lot to keep my plants in control in my small space.

Another tip, keep those cfl's adjustable. They should always be just an inch or two from the plants. With that setup, the plants will stretch to the light and you will run out of room with skinny plants filling up the area.

I don't know about the sealed room thing... I think the plants will be starving for fresh air (even with the CO2), but I could be wrong. Instead of worrying about heat issues and CO2, its easier to get an exhaust fan+intake hole and get even more cfl's in there. More light will produce bigger buds, aim for at 3000 lumes per sq. ft., preferably over 5000. I'm running at close to 15K Lumens/sq.ft. atm.