You should be able to get the plants even a little closer to light. When I use floro tubes I make sure the top leaves are almost touching the tubes. I adjust every day as plant grows. Never had a problem with burnt leaves. I think the key to optimizing floros is to get them ridiculously close to the plant. This takes more work because you have to adjust every day at a minimum. It does make a big difference.... sometimes I will check my babies under floro tubes many times thru the day....always fiddling, trying to get a little closer!
I have not tried using CFLs......I think they get to hot to allow leaves to touch or get as close as with the tubes.
I would advise no more than 1/2 teaspoon per gallon of water (if it is the powdered Peters in a little tub.). to start out....gradually increase to apx 3/4 teaspoons per gallon. Be extra careful with keeping the dilution low and you can feed every time you water.
And if you don't have a moisture meter, you should, as it will make it easy for you to tell when it's time to water (feed).
Also I can't think of any advantage to foliar feed at this stage.....you want your little plants to develop strong roots quickly, this could be slightly hindered by foliar feeding now. I would do it only to correct a deficiency at this stage.
Good Luck