I would not suggest putting a wave maker on your return line. That you want to be running continually.
I used the SCWD that you linked before but I used it on a closed loop for my first SW
setup. Eventually it wore out and I had to toss it.
As for power heads, well that depends a lot on the kind of SW
tank you are planning. If you are going to have a lot of SPS
corals then you are going to want higher flow. If you are planning on have more LPS
and soft corals then you wont need as much flow.
I used several different kinds of power heads and found the Nano Streams (Tunze) to be the best for flow and life. You can also use Korallia or even get Maxijets and put the sureflow mod on them.