1. we DON'T know the parachute man...he's new. he's the guy who's been on the sat phone.
2. YES...it's all flash-forwards now. The producers said that at the halfway point of the series (which was the finale of season 3...an episode that had BOTH flash forwards AND flashbacks...) they were going to stop doing flashbacks and do flash forwards.
3. i missed the reference to the "oceanic 6." though i do believe that some people do leave, some people do stay. obviously, we know that jack, hurley, and kate left; we know that kate is happy to be back, but that jack is not and that hurley has been driven insane by it (i think, insane with guilt because he knows the other passengers are still on the island and still alive, but it's a secret they've agreed to keep...like when jack asked him point blank, and when he lied about knowing analucia or having any idea what happened to her). whoever was in the coffin at the end of season 3 came back, too.
4. who do you guys think is in the coffin? there are soooo many people it could have been, if you consider that nobody came to the funeral, and the number of characters on the show who have no family or friends...locke, sawyer, ben... someone i know suggested that maybe it was michael, while walt maybe stayed on the island. my official guess is ben, because of how hateful kate's voice was when she said, "why would i want to go to THAT funeral?"
5. when kate says "he'll wonder where i am." at the end of season 3...did she find a new guy, or is she with sawyer?
6. i think john locke clearly stays because he has always had a special connection to the island. i think bernard and rose (the older couple with the black lady and the white man) are going to stay, because rose is another person who experienced ridiculous healing from the island (she had some inoperable, incurable disease which disappeared on the island). i think sun is going to want to go, because she's pregnant and may die if she stays to try to deliver...and i think claire and the baby are going to leave (because desmond saw it happen in one of his visions).
my guess about the nature of the island is that it's kind of like a hub, a port, a window between alternate realities. so if jack, kate, hurley, etc. get on one helicopter and fly home, they won't come back to the same reality, the same version of the world, as the people who get on the next helicopter.