YES to your last three points in particular. Didn't Caleb also refer to her as "pretty," too, or am I misremembering? Either way, how he refers to her when they were young has creepy written all over it.

I would not be surprised if Norma and Caleb's father was killed by one of them, and my money would be on Caleb. My impression of Norma given events last season (asking Dylan for a gun so she could protect herself but clearly being very nervous about the follow-through) is that she's never killed anyone.