I really to need to read the books form the sound of it.
You really should. The first three might take a little "push" to get through, since Harry is still more like a kid than a mature teen. There is plenty of violence, but its contained in smaller bits and mostly to the end of those books from what I recall. The last three are likely to have you buried in them wanting to do nothing but read and break for food (well, that was me, anyway ) Goblet of Fire (book 4) really gets you ready and "bridges" the first and last three, preparing you with the increased length and maturing content.
Anyway, for the expansion...I'm gonna be going through withdrawals once facades start going up. I almost like seeing the structural work more than the themeing.