I just finished. As for those still left with all those questions (the numbers, the shit that happens on the island, etc), I think it's fairly obvious.
The Island is limbo, purgatory, whatever you want to call it. The Others are the keepers of this place, led by a "Peter-at-the-gates" type of person. The decisions that people make on the island (working together, who they follow) affect whether they go to heaven or hell at the end. There was an obvious "Devil" character, prophets, et al.
All of the bad shit that seems to happen when the characters try to leave the island is fate telling them to let go and just accept what has happened.
This allegory seems pretty obvious, given that people who died come back to life to guide others, there are supernatural gifts granted between characters, and, overall, things happen that seem to be unexplainable without divine intervention.
I fucking hated all the sobby reunion get-together crap at the end, by the way.