Good points, Jazzman.
As far as whether or not Dumbledore was up to something, something he says (on page 553) tipped me off to the idea that perhaps all was not as it appears. He tells Harry, when asked about what others might think of him leaving the school, that "I am off to Hogsmeade for a drink" and "I sometimes offer Rosmerta my custom...or I appear to. It is as good a way as any of disguising one's true destination". I also caught what Jazzman pointed out regarding Draco, and the Pheonix connection as well. Thanks for saving me lots of typing, Jazz- my fingers are killing me from painting all day!