5. How do they get off the island?

As we saw at the end of season three in a flash forward with Jack and Kate, the Losties do eventually get off the island. Jack also seems to believe this was a bad idea, and that 'we need to go back!' Why he is so depressed, and desperate to return is uncertain. Who it is that dies in the present day and why Jack and Kate are no longer friends is also unanswered. Charlie was told that if he died, his death would lead to them being rescued.

There is a ship coming to the island now, but Ben seems to believe these are bad people (funny coming from an insane sociopath, but still). We know that they get off the island, although "Lost" cretor Damon Lindelof has stated that the flash forward we saw is in the middle of the story, not the end. So how do they get off the island, and who survives? Who dies, and/or is left behind? Why does Jack seem so upset and possibly guilty over being back in the real world?