Good questions-- I may be wrong, but my understsind is that pretty much a full season of Lost was bought based only upon a one page "concept" outline. No scripts were written when the show was bought.
What's more, I have heard that Damon and JJ got together and sketched out pretty much the whole show before they wrote a single script. I vaguely recall hearing that they felt they had about 100 episodes worth of story to tell.
Obviously, the will be more more than 100 total episodes of Lost (unless they plan to end it next season, and I think they would have to rush things if that decision was made). I think that a fair amount of what we are getting now is "filler" that was not part of the original story. But, I also think they are giving away secrets and details and plot twists that have been there all along-- they may just be adapting them as they go.
For example-- the original plan may have called for the "Penny" character to be someone connected to Jack but they changed the show when they added the Desmond character and wanted to expand on his history. I suspect that they never planned to get into "The Others" nearly as much as they have and that Juliet was certainly never planned. But, when the audience suddenly really connected with Ben, they decided to make him a huge part of the next season. I think one reason this season has felt somewhat disapppinting is that most of this year has been stuff that was not planned from the start and probably will not matter very much in the end.
I have no problem with any of this. Just because the show was planned in one way, does not mean adapting it and altering it along the way is a bad thing-- heck, it would be foolish to not do this and doing it has given us characters like Desmond and Ben who are among my favorites on the show. But, the producers/writers need to keep an eye on where they have been so we do not get inconsistencies that anger the audience.
I am still eager for them to pick an end date for Lost-- I think 5 seasons makes a great deal of sense-- and to see the scripts start to take us toward that end. While I will miss Lost when it is gone, I will be very disappointed if they turn it into an XFiles or Alias where it loses its focus and goes in such random directions that the audience no longer cares.
-Jason "I am confident JJ and Damon have their eyes on the finish line and will end it in at the right time" Evans