As for the sequel... yes. They're doing Prince Caspian next, where all four children go back to Narnia. All actors from the first have agreed to play in the next. It's slated for Xmas '07.

I find it funny about the references to Christian Mythology... Lewis himself once gave an interview where he admitted recognizing how the book and the story of Jesus matched, but that while it may have been an influence, it was not supposed to be a copy of.