Hawkes is hunting a reanimated human(s). Hesitate to call them zombies bc I have yet to see any flesh eating.
I think this is true. The scientist on the lam kept Annie's body in his trailer (which now just has an effigy in its place) and when they found the magic bacteria they're drilling for, he put some into Annie's corpse and she reanimated.
A select few of the townies (however connected to current/past victims) are receiving ghostly visits from the dead.
The vending machine guy made it sound like just about everyone sees ghosts. But, to your point, Travis came back to show Rose the corpsicle. Turns out Travis is likely Rust Cohle's (season 1, Matty M) father.
The town of Ennis depends on the mine for it's livelihood although the water (possbly only in certain areas) is tainted and there is at least from what we have seen, some evidence of stillborn deaths.
I think this is the likely explanation slapped on it by the folks you mention below. Fuck it, mass hysteria/hallucination caused by chemical poisoning. Put it in the X Files and let's head back to HQ.
Anchorage will be handed the task of performing post mortem on the thawed bodies/corpses of the research team... minus one.
Yeah, I don't think there's going to be a great revelation/wrap up here.