Lighting hours!?

Just germinated my seeds i have greenhouse cheese seeds!

when potted what hours of light should i have!?

and for what period!?

how close?

i have a 600 watt MH is this ok?

What temperature must it be at night...

must i have a fresh air in take?

600 MH is fine
Use the back of your hand to test the heat. I would start at about 24 inches away and work down from there.
18 hours on 6 hours off
temps should be around 72 all the time
Fresh air exchange is essential

76-78°F is ideal
You don't need an intake fan if you have a powerful exhaust fan and a passive intake hole