There is always more than one way to skin a cat.
Having the pot and pump in the engine bay would make the pumps job slightly easier, shortening the distance from pump to reg. but would be suprised to see the fuel be cooler with the pot in the engine bay.

The way im doing mine is build the swirl pot into the tank this keeps the fuel at the most constant temp and gets the weight as low as possable.
I will have the return going to the tank (im open for further debate on this but im going with what i have read and makes sense to me).

The tank will be insulated along with the fuel lines and rail. I have a mate that logs his fuel temp in the tank and it gains about 10 degrees c during a 10 lap race, thats why im putting in the extra effort of insulating.

All that aside, the system will work fine with the fuel return going to the swirl pot or to the tank. Those carter pre pumps flow plenty..