Just buy the bat insulation for 2x6 walls and pull it in 1/2. It generally separates very cleanly along a cosistent plane. It does create a little more airbourne dust than cutting, but i would recommend wearing a proper ½ mask respirator anyway.

Civil Engineer here. You do not need a grinder (macerating) pump unless you have a discharge pipe less than 2". If it's a 2" discharge, i would go with an ejector pump. It will pass a 2" solid and is less complex and more reliable than a grinder pump. Definitely do NOT replace it with a regular sump pump. If you dont know (and/or can't see) your discharge pipe size, i would replace it with a similar pump.

Its a drip cap. Not a particularly well constucted one. If its raining, even a slight breeze can blow the rain against the exterior wall and it then runs down the wall. The drip prevents it from flowing into the small gap betwwen the top of ghe window or door and ingo your house