My 2¢, your problem is/going to be ventilation. You need ventilation to keep a certain range of temps. Now if ambient temps rise and you don't have proper ventilation you'll see your room temps rise. That's what you need to be worrying about
As for you light question, move the lights 'With' the plants growth. Natural stretch will occur inbetween nodes but if you don't have much space between soil and your first node, go for a little stretch so its much easier to transplant.
One more thing, young plants (seedlings and freshly transplanted clones) don't take up a lot of water. So its easier to put them in smaller pots with less medium. I cut bottoms off dixie cups about 2". If you're medium has water in it, don't water. the roots with travel to the moist soil when they need water. when your plant builds a good root system you'll see the medium dry out pretty evenly.