I'm pretty sure the island time is before what we know of as present day. I think that's how Jack's dad's body ends up missing from the casket. If they actually went back in time when they landed on the island, even if it was just a few days back, Jack's dad would not be dead...thus, the casket would no longer contain a dead body.
I like Dan...I did even before The Constant.
Do we know absolutely for sure that the book that says "Desmond is my constant" is Dan's notes or is it possible that it is a note written by someone else who gave Dan the book? And, yes, Desmond and Dan did cross paths before Desmond left in the helicopter.
George really creeped me out at first. I thought he bore a striking resemblance to the one shot that we actually saw of Jacob in the cabin. I was just sure we were going to find out last night that when George was being transported in time-space, he was being transported to the cabin...flickering in and out or something...somehow caught there. And this is why he was begging Locke to help...because on the ship, he was strapped down and having to endure the constant switch between time and space. But since he apparently dies at the end of the episode, I guess that is going to turn out to not be the case.