my 20 gallon long question's

I plan on just using gravity for the supply into the sump, since I do not have glass drilling bits. I might drill tho, I have not started the sump just yet. getting materials in order.

I got a 550 gph return pump which should work out good enough for about a 4-5 foot height.

 

You can get glass drill bits at glass-holes.com. A 20L is really easy to drill. I did mine myself for my fuge tank.
If you do not drill, I would not recommend that overflow in your link. That is a half-reared copy of a CPR, which in themselves are a PITA to begin with, I could only imagine what it would be like with all the safety and suction he removed from it. Get an Eshopps overflow.
I also would not run a bio-cube skimmer in there. Use your existing skimmer, it will be fine.

 

So yesterday I found a local guy who sells aquarium supplies, sand, rock, even fish out of his garage out here in az. I picked up a CPR AquaFuge 2 Hang-on Refugium for 70 bucks with a small powerhead.


Trying to figure out how exactly I am going to plumb this into a sump.

This is what the back looks like (not my picture, just found it online)

http://www.mesker.us/images/for-sale/cpr-refugium-back.jpg

I am assuming I hook up the powerhead to the smaller pipe on the right, and the water will come out of the bigger pipe. I am guessing I will need some type of powerhead to pull the water out of that, and down into the sump.

 

Here is a nice link with some more info:

CPR Aqua Cave 2

You can also google search for the instructions, but you are correct on the pump. Are you thinking of going this route instead of the overflow and sump? Lot of good advice on the sump, I kinda wish I had gone that route to being with. 20 Long does not have a TON of real estate to begin with and every piece of equipment you add is visible. The CPR will leave the pump visible in the tank - good news is you can then hide the heater.

It's all a matter of comfort, but for what it's worth, the sump will give you a better chance of a more stable system and will get most of the equipment out of the display.