I have dual overflows and am running a mag18 as a return pump. I also have 2 wp40's and a koralia 1050 for now.
If you can I would go for a higher return pump, mine barely has any flow after the head loss, I would have gone with a mag24 if I had the choice but I had the 18 already. lol
I'd also figure in some plumbing parts like a GOOD check valve for the backflow from the pump and a ball valve to tune in the pump. Unless you are going to go with a DC
return pump that is adjustable. I've heard good things about them but they can be pricey.
Also, you should pick up at least a 10g tank, maybe even 20g tank for the water reservoir and an ATO. The amount of evaporation on that size tank is pretty high so you dont wanna be putting water in the sump every single day, sometimes twice.