Inside Exhaust? What am I not getting..

[GrassNewbie]

what bulbs and reflectors you gonna use?
how many plants you wanna grow?
and if you wanna but the heater with thermometer MAKE SURE IT ISNT DRY HEAT...like fan heaters,cos they can damage plants baddly,and what hight is your seeling?

2x600w in cooltubes (like on the pictures), plants a little over 20 SOG.

Ceiling height is 7', so pretty low.