Green leds are safe to use in grow rooms after lights out the red could case an issue but would have to be within inches of the plant to have any affect.
I have been using protect t for years and haven't notice any wild swings in ph. I use the 3 part std gh products and always put the protect t in last then ph to 5.5 with a couple drops of ph down and it stays very consistent for the 10 days until the next res change. I use a drip to waste system.
It looks like you can wire at 480v or 120v Find the black wire or wires on the ballast most times they are marked with a tag 120 or 480 sometimes it might be marked right on the wire itself and use the 120v tap and the white wire is the common.
I second the Eagle 20 solution but as stated you need at least 2 weeks before harvesting. I treat in week 1 of vegging and in week 1 of flowering just so I never have to see that crap again what a pain that stuff was.
Use some of the mosquito dunks you can get at hardware store mixed in water and flood the soil in the pots. Or you need nematodes for the soil to combat the gnats.
Pollen from the males rides the air, on bugs and on the person growing them if you have any air movement in the room they are in they can and will probably pollinate the females.
I have seen from 8-12 hours of continuous darkness work depending on the strain. I don't think I have seen anything other than auto flowering plants flower with less than 8 hours of continuous darkness.