Yes
Now this may be a little oversimplified. But I would think that the easiest way to conserve water would be to recycle it. An example of that would be the new car washes that recycle the water that...
Between a 500-gallon-per-minute pump and a 2,000-gallon-per-minute pump.
Yes, You pump from one pump into a second to get a greater pressure boost. Be sure that the pumps and lines can handle the pressure increase.
You measure the distance from the surface that mounts to the block to the hub where the pulley mounts. Short=5 5/8" Long=7"