[Snowflakian]

So far all I've figured out besides what's already mentioned is:

Smokey can't leave unless all the candidates do. One of them would be the new jacob (Hugo?), so they all have to leave. The law of balance on the island makes jacob the yang to smokey's yin. So he can't leave unless jacob does, and since he doesn't know which will be the new Jacob, they all have to leave.

The statue indeed had 4 toes, that mystery is still around. Though why it broke is sorta explained with how the black rock got where it is on the island. Still leaves the mystery of what the statue was, and why the temples exist.

Smokey needs a dead body who's soul isn't trapped on the island to take over.
First the Doc's father, then John Locke.

People who die on the island, souls are stuck on the island, due to the same magnetic forces and other weird attributes of the island, like the ancient time dislodging device. Not exactly limbo, but sort of a 'man' made one too. This is what I'd assume keeps smokey from taking the form of any body he chooses, and why it has to be a body that died off the island.

Smokey was once human before he was marked into what he is. (mark of cain? Speculative.... But eden does fit many of the attributes mentioned previously, or at least the place that inspired those legends.)

The AU is the current problem though. They seem connected to the island people, but what happens if the island people leave? Earth shattering paradox? Since the island is sorta outside time and space? Or will they just merge with their AU selves into these new lives? Personally I lean more towards now they can't ever leave or else the paradox happens.

The AU seems to have sunken the island during the nuke, so I guess that means this is the junction point of the change. Things that would have happened because of the island now didn't. Ben left as a kid with his dad, Russo never went to the island after the fact, and so on. Probably even changing the doc and claire's dads interaction with the island. No clue how whidmore and his wife know this though.

There's been more explained too, but without the eps in front of me, I'm drawing blanks, since honestly the only thing I care about is WTF is the island itself.