W/r/t the pump location: if you have some leeway, mount the pump as far below the tank outlet as possible (keeping the pump body and lines well protected by the frame, bumper, etc.).
Gravity pressure is all you have to prime the pump, which is directly proportionate to the height differential between the actual fuel level (not the bottom) and the pump. Pump 12" below tank level has twice the inlet pressure as 6" below, etc.
