I'm sure the whole Locke being dead thing will be explained this season. I have no clue as to how though.

Do you get the Sci-Fi channel? If you do, did you know that every Monday night they show 4 episodes? They started from the beginning, not sure where they are at now.

As far as how many seasons are left, I thought that there were just 2 seasons left, which includes the new season, but then I heard there might be two more after that, for a total of 4. So not sure which is true. I'm sure that will be discussed once they start promoting the new season.