ScottH, rest assured Chase is quitting the show, HBO isn't quitting him. That's important to keep in mind since it isn't like some network is stopping him before he can tell the story he wants to tell. Originally this was going to be it, then he needed more episodes, then he neeeded even more episodes. I'm not sure where it stands now as I stopped following. I'm comfortable knowing that HBO is (and always has) providing him the blank canvas he needs to tell the story he wants to tell.
Nah, HBO will most likely pull the same stunt they did with the Sex in the City DVDs. two separate volumes for one Season released at the standard price.
Travis is right. There will be the upcoming 12 episodes and then an additional 8 that will start airing in January for a total of 20 new episodes. That's it and Chase will not do anything beyond that under any circumstances.
A fairly serious spoiler from Jeff Wells about the first episode, nothing specific though: I just finished season 5 and it will be torture waiting nearly a week for season 6.
Here is a link to an article about the first episode. No real plot revelations, but some detail. Depending on your tolerance for spoilers, read at your own risk.
Judging by the poster, I think Melfi dies in the first episode (apperently some shocking happens). If you look at the poster she's standing behind a door almost like a ghost, so I'm gonna take that a sign. The Sopranos posters have always been very literal. Take a look at the Season 4 poster with Paulie in white facing away from everyone.