I'm glad you liked the opening speech. As soon as I realized that I would be writing Snape as a teacher, I knew I had to come up with a opening speech for him, given sterling examples of Snapish opening speeches in canon. I was a bit worried I wasn't up to the challenge.

Ginny is the result of one of my friends' (my sort of beta, actually) complaining that she had a somewhat poorly developed personality in canon. I think of her less as a bitch (though depending on the teacher, I'm less than fond of the hecklers too) and more as a sort of later day lady marauder. She likes to throw the fox in with the chickens without considering that there might even be consequences to others. It's an enthusiastic thoughtlessness.

Harry is in the deeply unfortunate position of having a secret hidden from intelligent people who know him very very well. This can't last. *grins in the frightening author way*