Movie age limits ∵ bishwhacked

Well, I have the good fortune of fighting a cold today. Thankfully, the kids have been in good moods and Martha's been sweet enough to let me sleep in and has assumed most of the load of entertaining/directing the kids.

I started watching the extended edition of Fellowship of the Ring while they were napping. I made it an hour in before Joey came out and asked permission to 'wake up'. I, of course, paused the movie and began mulling over when the right time would be to introduce him to the Lord of the Rings series and even Star Wars. He knows of Star Wars... I have too much licensed product in my house for it to be avoided. almost enough Star Wars stuff and he's asked me who a few characters are, what ships are called, etc. But he hasn't seen any of the movies.

I'll confess that I long for the day he digests the Star Wars and Lord of the Rings movies with me. They'll be important days in the geekling's life. They'll be planned out, scheduled for, and celebrated.

But before all that, I have several questions to ask myself. I figured I'd share mine and perhaps collect a few from you.

How much stock to I put in the rating system that's already in place? (G, PG, PG-13, etc.)
How much violence is too much? Is there such a thing?
When do I want to talk to my son/daughter about killing in movies/stories?
When do I want to talk to my son/daughter about the need to kill?
How many years of love will my kids need under their belts before they face the likes of the Lidless Eye or Darth Vader killing Kenobi? Or Luke's whining, for that matter?

I'm sure I'll come up w/ more. How will you decide when to expose your kids to these stories? How have you decided? Thoughts?