Do you know if you are planning to do a sump/fuge? If you don't you can get the reef octopus skimmer. It's a HOB
. I have a 55 tank, and I use the bh-100. It was like $125 when I got it a couple months ago and I love it. I do have an emperor 400 hob
filter, however from reading this, I may actually remove that since I have a ton of LR
and 4 powerheads and the skimmer.
The powerheads you posted look okay. I would go w/ 750gph I dont think you need more than that. I would buy two of them. 1 for each side of the tank, face them at eachother. You may even be able to go two 500's. I use hydro korolia's. I got two 750's for $30ea. from Dr. Foster & Smith.
With a 4 bulb t5 light, you can keep a bunch of softies but not too many corals with that fixture. Many corals need 6-8 bulb or LEDs. I currently have a 4 bulb as well, just wish I spent the extra $ in the beginning on a better system so I can have corals I actually want.
Best of luck, will be following along.