Sounds familiar...just about 7 months ago I upgraded from my 6+ year old 46 bowfront to a new 75g drilled. I transferred some things, and chose to leave others behind. I learned a lot and researched and am really happy with where I am today.
Sump: trigger systems ruby 30. You can get the larger 36" but I opted for this one because I needed space in my stand for dosing pumps and jugs.
Return: mag 7. I equipped a ball valve in the return line to fine tune, but found that it works best wide open. I question if I should have gotten a mag 9 and dialed it back a little, but the mag 7 gives a nice flow through the middle chambers refugium and works just fine.
Regarding heat, I have my heater in the first chamber, a digital thermometer in my return chamber, and a digital thermometer in my display. My return area is normally .1-.2 degree F warmer than my display.
I would also say my return is quieter than my skimmer