This is BettaBaby's husband.
The Genex pump is an alright pump, but the plastic it is made up of is somewhat brittle. I have installed a Genex 4000 on a tank before for circulation. It can be used internal or externaly. When dealing with larger volume pumps, I prefer to use external drive pumps as large internal pumps will heat the water up pretty good. External drive pumps still transfer heat, but not as much as a large internal drive pump. If you have a standard 120 with two overflows, you will have one 1 inch drain and one 3/4 inch return per overflow. Each one inch drain can comfortably handle 600 gallons per hour for a total of 1200gph. You can drain more than that thru it, but the more you do the louder it becomes as the water pulling air down with it makes a loud gurgling sound.
You will need more circulation than that in the tank which you can achive by using power head, etc.
I would recommend either a posidon/velocity (they are actually the same pump) T4. They are about 1250gph and are made of titanium. They are also ultra quiet. Other good pumps are Coralife TurboSea, Iwaki, and Blue Line pumps. For the money, the Velocity T4 is a good deal as it will last for a long time. It will not corode or rust and are very reliable.
For accesory power heads, I would suggest one of the newer style high flow pumps. There are a few different brands, Tunze Turbellaflow, TAAM Seio pumps, etc. These pumps are not like standard power heads. Instead of giving a hard dirrect linear flow they deliver a broad stream laminar flow of water that more similates the natural current found in the ocean.
If you have specific questions we can answer them for you. There is too much to cover to go over a setup in general and would make for a very long post. Better for everyone to take it one question at a time.