I haven't been posting here all season, because I watch in the UK, so I am 4 days behind, but this is the greatest show ever!
Just a few observations
It seems that the show is destiny vs free will. At the start of the episode, when they are talking about the people on the black rock (one of whom most be Alpert), he talks about how they are always corrupted by the island. Here, this is a case of destiny, and the evil guy is trying to break that, with his loophole and kill Jacob.
The evil guy, who I think is smoky, has somehow caused the loop, where people come to the island, and are corrupted, then die repeats. However, something has changed that. It is not the nuke, that always happened, as shown by the radiation that Sayid found in the Swan, but it must be Locke coming back, and I think it was Hawking's role (unwittingly) in trying to repeat all the original conditions, but with one slight problem. I believe that the monster somehow chose Locke at birth. That is why he drew the smoke monster when he was young, and then why he blew up the sub and the flame. I know it does not make sense, but its the best I've got
Oh, and about the guy in the cabin, they had not properly cast the part then, I don't think that guy is the right person, though I believe it was a physical manifestation of the smoke monster