I would do a return for where you live, as you will get cooler fuel from the circulation.
The regulator can be placed pretty much anywhere in the return, but don't know about the vacuum part unless it's for referencing the pressure for some reason.
(usually referencing is for boosted applications)
I'm sure their directions cover that.
Hey TrailBeast, thanks for recommendation on return line to keep fuel cool. However, you mention to put regulator along Return? Shouldn't it be Before fuel rail? Help me out here please