1 - Getting rid of the garbage statics can be difficult. I have had no problem with just deleting them. But for the mod to work it usually has to be dead last in the load order, or almost dead last. I don't know why. Even then it does not always work.
2 & 3 - I did not even know about static collections!
4 - Some bodies never disappear. The two raiders who threaten Trudy at the Drumlin Diner are like that. You can just select them, and use the markfordelete command. Then save and reload. That will permanently remove them from the game. Just be careful to make a different save before hand, because you might end up deleting something other than the bodies, like the ground!