Investigating a serial killer with 26 victims wouldn't be a town sheriff's authority. Angel Falls would be swarmed by higher ranking investigators at this point.
The killer picks those who, or whose parents, own a business in Angel Falls. Jimmy Carruthers makes no sense as a target, as his father opens his only after, and because of, Henry Walters' death.
During the cinema kills, Winnie needs the flash of her camera to see anything. The killer, however, can see well enough to kill two people, despite not being a supernatural entity (as he can be killed by a chest stab).
After Winnie "helping her", Bernie can remember the alternate events. With this logic, so should Aunt Gale, as she was also saved by Winnie.
Nobody with a minimal empathy would use a mocking nickname coming from school bullies to address their love interest.