Hello new here. advice on setup

[tbone]

Hello.

i'm new to the forum
need some advice.
I've recently moved to a new home. decided to setup my SW tank up again.
90 gallon tank with 40 gallon sump,
i have all the sands and rocks, sump, and skimmer etc. I'm currently sanding down all the paint from my stand and canopy.

I'm not so sure what type of paint i should be using.
i have exterior alkyd oil base paint, is this reef safe?

also i have a metal stand. there is a lot of rust on it. got most of the rust out but, will this be OK to paint over?

lighting question.
I'm not sure what type of lighting i want but i would like to go to MH later on once I'm done school as i don't have much money.

i currently have 2 ballast OD 2x on 4 lamps. running T8.
i was looking toward changing the setup to maybe t5 and adding MH later on.
does anyone know where i can find t5 ballast and tubes?

one more question please don't kill me :P
when i had my tank setup. i had noise issues with water falling down to the sump. i've tried drill a hole to allow the air out but it didn't work too well. as well i don't have a overflow box. not sure if i should try and put one in.

any help, advice will be greatly appreciated

how much sand is too much? 4-6 inch? i think i have somewhere around 100lb of sand