Gonna shed a little light on things here, not that I have many more answers than you all.
1) As others have said, it really IS going to run as 1 encounter/week. Chris mentions in a blog post (here
) that you *can* opt to run more adventures, but there are downsides to doing so (IE - if you run all 4 weeks (one chapter's worth) of adventures in a single day/night - you'll have nothing to play for the following weeks).
2) When you opt to export your character from Undermountain: Halaster's Last Apprentice into LFR, one of the ways/reasons you'll be able to do that is because of the new Retraining rule. I suspect (but don't know - this is ALL me/my speculation) that D&D Encounters characters will use the "base" RPGA Character Creation Rules, or the D&D Adventures will have its own appendix for creation rules. It's been said that the CCG is going to be split into multiple documents in the near future: General, LFR "appendix" and I would expect a "D&D Encounters" appendix as well. That's just my personal speculation, however.
3) It's been said you can either grab a pre-gen character (most likely options for walk-up and new players) or you can bring your own 1st level.
4) It's possible that future seasons will start above 1st level (though, being aimed at casual/new gamers, I doubt we'll see play that goes beyond Heroic Tier) however the first two Encouters program (Undermountain and DarkSun) are for 1st level characters.