I recently bought a 29g to set up with my 20g and a few other items and want some of yalls advice.

I started out with a 20g with a 3" sand bed, 1 250 gph powerhead, a Marineland powerfilter, and a 175w 20k XM.

I have a 29g for a display, 20g for the sump, and a 5g minibow for the fuge. The sump underneath will house a quiet one 3000, and 20 lbs of rubble rock, a protien skimmer and necessary plumbing. The display I would like to be bare bottom, drilled for an overflow, and HOB return plumbing and 40 lbs of live rock. The fuge will placed above the tank, and fed by 3/4" tubing, with a ball valve for flow adjustment, and returning to the display. I would like to keep lps and sps, maybe zoos across the bottom. As for fish, I currently plan to get an Algae Blenny. Havent decided on others. Now for the questions.

Can I use a plenum DSB in my sump? I understand flow cant disturb the sand too much.
My tiny fuge is too small for an effective DSB but with both together can it be done?
What size should I make my overflow?
The pump is rated for 780gph, it rises 3' to the display and 1' higher to the fuge. I estimate 475-550 gph to the display.
I Bought a new reflector from hellolights to go in a DIY canopy I made, but I am wonder about using tin foil to cover the rest of the inside. Will this create more heat?

These are just for starters. I would like any suggestions, ideas, questions if I am too vague. Thanks, greasemonkeysatx.