if i tick that little "respawn" box on a random NPC let's say Edger of Edger's Discount Spells and then kill them what will happen? will he respawn where he died or will he not respawn because a certain protocol is not met. and what if i dont kill h im wil his invintory just reset every three days?
You don't want to kill a character like Edgar, you'd be totally screwing up his behaviour package. There's two type of characters, one who can cross from one cell to another, like going through a door, and one who can't, like a random bandit. Selecting respawn on an NPC will make it so that he can no longer pass through different cells. And he needs to be able to do that as part of his AI package. There's no telling what might happen if he can't fulfill part of his routine, you may never even be able to get into his shop anymore. As for his inventory, yes it will reset every 3 days.