I'm new to 9-12 and enjoyed reading the Lost thread last night. I, too, at first was so frustrated with the ending, but then everytime I watched it after that, I cried my eyes out.
Anyhow, this is the best explanation that I could find on the whole series. It helped explain a lot of things I think the writers/producers left out or never really explained fully.
https://www.eonline.com/uberblog/watch_with_kristin/b183078_idiots_guide_lost.html
Re: NBR: For all you Lost fanatics...