If you can afford to buy some air cooled cylinders, do it. If not, make them, find out here, www.overgrow.com
Hook up some ventilation ducts through your lamps, Ive never done it, but Ive read about it..
tells you how to do it on overgrow.. run air in, and air out..

You'll need duct fans leading outside somehow to bring in fresh air.. blowers, something to get the air in, and the air out
www.insidsun.com or www.discounthydro.com

As for vegging small plants, you will probably need less powerful lights.. those are way to high in heat to keep close enough to your plants, I'd say they'll grow, but not at full pace and you will probably encounter problems..