?#1. use the biggest pump you can fit in the 2’x2’x2′ pit. Use a pump with 2″ sphere size through it. a 2″ ejector.
?#2. 2″ pipe out is OK because the 4″ in is by gravity and out will be under pressure by the pump.
?3#. The pump “OFF” pouint should dictate the leave in the pit.
?#4. The pump should be hard wire in a water tight junction box. This will require a “disconnecting means” with in sight of the pump. This is just like your AC unit outside. It has a “disconnecting means” so it can be worked on safely.
Go to http://www.zoeller.com and look at sewage pumps model M282(100 GPM@10′) and M292(125GPM @10′). These are the biggest 115V unit we make. If you have 230v available M284(135GPM @10’or M294(180 GPM@10′) we make a M295 (195@10′). I would use M294 if 230V are available. The reason to use a solids handling unit is to handle the leaves and stuff that will come to the pump.