Star Wars Holes?

Just saw Episode III.  Here are my unanswered questions.  If you have answers to these, please let me know...

  1. They are concerned about hiding Luke and Leia.  Why in the hell would you hide Luke with Anakin's step brother in a place where Anakin's mother lived for 10+ years?  Wouldn't Darth be able to sense that?!?  And is hiding Leia with an Imperial Senator the smartest thing?
  2. In Episode IV, why doesn't R2 remember Obi-wan?  And why doesn't Obi-wan remember C3PO or R2?  He spent enough time with them at crucial moments in Episode III to have to remember them!!
  3. In Episode IV, Ben says a few things that now don't make sense:

    LUKE: No, my father didn't fight in the wars. He was a navigator on a spice freighter.
    BEN: That's what your uncle told you. He didn't hold with your father's ideals. Thought he should have stayed here and not gotten involved.
    LUKE: You fought in the Clone Wars?
    BEN: Yes, I was once a Jedi Knight the same as your father.
    LUKE: I wish I'd known him.
    BEN: He was the best star-pilot in the galaxy, and a cunning warrior. I understand you've become quite a good pilot yourself. And he was a good friend. Which reminds me...
    BEN: I have something here for you. Your father wanted you to have this when you were old enough, but your uncle wouldn't allow it. He feared you might follow old Obi-Wan on some damned-fool idealistic crusade like your father did.

    A couple problems with this...  Obi-wan talks as if Anakin actually knew Owen Lars for more than a if they grew up together and then Ben came along and dragged Anakin off to war.  Plot hole, or is Obi-wan just lying to Luke?

  4. In Episode IV, when they are all sitting around and Han jokes about Ben being a Jedi, how come Chewie doesn't chime in and say, "Jedi!  I knew a Jedi Knight 18 years ago.  Do you know Yoda?"
  5. In Episode IV, Darth is at most 50 feet away from Luke both in the hanger and in the trench.  He can't sense him??  He can sense that Obi-Wan is in the Death Star, but not that his own son is there????