First of all, I seem to have developed some sort of conscience recently (it's probably Blaise's fault), and this has been bothering me for a while, so this is the only time you'll hear me say it:
Sorry I've been so hard on you lately for "thinking". I realize that the position you're in can't be easy, and it must be difficult being away from things you know and being expected to be able to take charge of things.
That being said, I want to help. School is completely boring and stupid. I got your owl about looking into the protection spells--Dra Antoine, except for the basic ones around the dorms and classrooms, basic magic can't undo them. And I'm not going to try anything big because there's a security charm done into the bigger ones so that if someone tampers with them, McGonagall will know. There are ways to get people into the castle, if you know where to look, and they have no spells on them whatsoever. And there are cases like your wardrobe trick last spring. I'm going to talk to Flitwick and see if he knows anything more about the spells around the castle walls.
I don't know if that helps, but it's all I've got so far.
--P.