yep, if you drill, I'd use a 1.5" bulkhead, if not then a HOB overflow box for 1200 GPH. and probably a mag 12 pump for the return, but we will have to see how high you pumping to be sure about that. The set-up I like best for the fuge is to put the fuge on one side and the skimmer on the other and the return in the middle, I feel you have better control over your flow to each compartment that way. you would run 1.5" pipe to the sump then tee off to each compartment with a valve after the tee on each line. and then for your return go up to 1.25 or 1.5" pipe put in a union after the pump and then a ball valve, and be sure to drill a 1/8" or so hole in the return just below the water level in the DT to break the back siphon when the pump powers down.
If you can try and get some flex pvc, it will make the plumping easier.