ok.. first ? first.. yeah, the more light that you can get to the plant, the better of course..
now onto feeding your plants.. i am not a big fan of foilar feeding at all, and don't do it whatsoever.. as you have noticed, if you leave water on the leaves while the lights are on, the water droplets act as a magnifying glass and can and will burn the crap out of them.. whenever i water or feed, i always feed right at the soil line and try not to splash too much on the plants, and if any gets on them, i try to shake it off..
now, i like to feed my plants every other watering or so.. depending on how big your pots are, you are gonna have to water more or less often.. wait till the soil gets dry down about an inch or two between waterings.. i just use plain old tap water, but i let it sit out overnite so that the chemicals in it will evaporate before i use it.. if you have ph up and down, adjust your ph to about 6.5 or so.. i don't feed the plants any nutes till about three or four weeks old.. and when i do start to feed, i start out with only 1/4 of what the bottle says, and every week i increase it by another 1/4, so that after a month of feeding, i am up to full dose.. its always easier to feed them more if they are hungry, but its nye impossible to take away any nutes once you have given them to the plant..