Oooh hate to burst your bubble there, but the producers actually signed a deal for 4 seasons, if my memory serves me. The producers, in their infinate wisdom, want to end the show without stretching it out with filler. ABC, in their infinate stubborness, wanted to draw it out as long as possible for the money. They were in discussion about whether to do 4 or 5 seasons, and I am fairly certain they settled at 4. I might be wrong, but.... that's what I've heard.
As for deaths.... I doubt Locke will die. I have a friend, who has communication with some people behind the scenes... he's hinted to me that Locke is the most important player in the game.... the person that could tip the balance, as it were. If he dies i'll be surprised. But sawyer, I've heard nothing about. Now that would be an interesting death. I do know who's dying in episode 14 though.
Spoiler:
Are these confirmed anywhere, by any chance? Or just by word of mouth?
And Welcome to the boards!