Man I had to read that thing like 3 times I am so high. It's gonna be hard to get all the answers to your questions because there are so many, so let me say on the onset that your whole setup sounds great for a beginner so even if you just do what you outlined you'll do good.

For the nute formula I would go to the GH website and use their formula. I always use manufacturer's recipe.
I don't like rockwool, I think it is nothing but problems and costly overall. I would use hydroton in net cups.
Size of net cups depends on what size plant you want to grow. I personally would configure 5 plants in 6" netpots in bloom hoping to get 4 to harvest.
Beyond that its a matter of preference as to method. I don't like flood tables for instance. I'm more of a DWC or Aero/hydro.
herbie the love bud Reviewed by herbie the love bud on . any ideas with this ok ive been reading and reading on here and its been very informative. But i think i need to give all my info for a proper response from you guys so here goes....5x4 room with mylar on walls. 600 hps. flood and drain. 4' of space from light to flood table temps are 77 to 80 with light on and 70 with light off. rez temps are 70. 3x3 flood table with 18 gal rez.osilating tower fan and a good 400 cfm exaust fan running the aircooled light. using floranova grow and bloom for veg and bloom. in the Rating: 5