[Help] Return Pump & Other Equipment Questions

Hello,

I just got a 90g reef ready tank (Single overflow)(1" | 3/4" holes) with stand and canopy a couple weeks ago. Still have yet to test it to see if it holds water, but I'm not too worried about that. I'm here to get some help on getting the minimal equipment I need to get the tank running.

I just purchased 100 pounds of marco rocks, they'll be coming in the next week or two. About to purchase 90 pounds of sand as well. I'm looking to get the minimal equipment to get the tank up and running to turn the rock/sand live (I will be feeding it a live rock piece from a friend). I don't plan on getting any fish/coral until later in the year (When I can purchase a skimmer/lights.

So my plan is to get the following equipment to get it up and running:

SpectrePure RO/DI 90g refurbished unit Reef Octopus VarioS-2 DC Return Pump (will run external to lessen heating of water) DIY 40G Sump/Refugium combo (1$/g sale starts April 2nd, will get the tank then) 2 appropriate wattage heaters for a 90g tank with 40g sump/fuge

And obviously the bulkheads/plumbing for everything. And probably a drill/bulkhead set for the sump/fuge, since the pump will be running externally.

I know the RO/DI is basically a requirement for corals. Is that return pump okay? The reviews have all been amazing. Are lights required to turn the dry rock live?

Any tips/suggestions/anything you think may help? Remember, I don't plan on stocking the tank until well into the year (think August/September), unless I get the skimmer/lights before that (Saving for LED lights)

Any DIY sump/fuge plans out there? I've been googling, but haven't quite found one I like.

Thanks!