It's possible. Or they might have explained it away somehow. Muggles can be quite good at that where anything magical is concerned. I do understand why you wouldn't want to take the risk, though.
Rules may change, and they may have exceptions. Who knows how Preya will look a year from now, or five. You and I both know that
That's an interesting use of magic. Horrible, obviously, but creating an eternal winter and freezing people would require considerable magical talent. Perhaps you and your siblings have a few drops of magic in your ancestry, if you were able to use magical tools to stop her.
The connection of a ruler to his or her land is, in Britain at least, a very old sort of magic, and one that can be worked on non-magical kings or queens, too. It went out of fashion many centuries ago in Britain, probably because of the Roman tendency to but perhaps what you experienced in Narnia was similar.