LOST again

Obligatory spoiler warning.  You've been warned.

Going into the series finale, here are my most recent thoughts and questions.

• Who is David's mom (Jack's ex-wife)?  My guess is Juliet.  I'm pretty sure it's someone who was on the island and she's the only one I can come up with
• How do they kill someone who is already dead (aka Smokey)?
• Ben said that he thought he was summoning the Smoke Monster, but in actuality, "it was summoning me."  What the heck is that supposed to mean?
• Jacob visited Widmore?  Do we believe him?  It kind of takes me back to last week (or the week before?) when I began to re-think my ideas about Widmore being the bad guy and Ben being the good guy.  What if it's the opposite?  What if Widmore is the good guy, after all?
• How does adding Jacob's ashes to the fire make Jacob visible to everyone?  And why is he gone for good when the fire burns out?  Does that apply to Hurley, who normally sees dead people?
• How omniscient is Locke?  He seems to know things that other people don't, but he might be a good guesser, a good observer, or a good actor.
• Can Smokey kill Richard now?  Or did throwing him through the air simply knock him out for a while?  Once Jacob is gone, does Richard's immortality end or does it transfer to the new "Jacob"?
• Was Ben on the Monster's side all along?  I'm beginning to doubt him again.  For a time there, I almost trusted him, but maybe I was wrong.
• Why does everyone die if Locke leaves or puts the light out?  I'm not understanding the whole "light inside everyone" thing going on here.
• What the heck is Desmond's plan?
• How does Desmond's special abilities regarding electro-magnetism make him a fail-safe?  How can a person be a fail-safe?  I'm not sure I fully understand that concept.
• The rules have obviously changed since season ? when Ben went to talk to Widmore in his bedroom late at night.  I distinctly remember Widmore saying that Ben couldn't kill him, but Ben definitely dispatched him in the secret room.  Hmmm. . . .
• Why does Jacob sometimes appear as his younger self?
• Why does Locke want to kill Penny?  Was that just his ploy to get Widmore to spill the beans regarding his ultimate plan?
• Jacob has been watching these people - the candidates - since childhood.  How did he decide which people to watch?  How did he choose the names to write in the cave?  Did he have some knowledge that they would possibly end up alone?  And if they were chosen to be possible candidates because they were alone, why Sun and Jin?

I thought this was a shorter list of questions than it actually ended up being.  Oops. . . .  :-)