I've had some phenos that would always get it no matter what I sprayed or did with the environment and other phenos that never got it even next to ones that had it. You might have to throw that one away and start with different one
Spend the money on a good light. That's the one thing you shouldn't cheap out on. You could DIY with everything and as long as it grows the light is what will make the plant
I usually only veg on the table and they go to a bigger hydro system but night I would only do 1 watering the whole night cycle. Like halfway through it. If lights go off at 7am I would do like 1 pm
you really dont need that much hydroton on the table. I have none and my plants are fine but if you want it on there a little layer to just cover the roots is fine