To throw in a bit about the classes, remember that this is not Hogwarts, and isn't supposed to [i]be[/i] Hogwarts. Kingsridge has a different style, and a broader curriculum... So, I think we should come up with our own system, and not just copy whatever Hogwarts was doing in the 90's. For example, since Kingsridge is supposed to be for older students anyway, having more choice in individual curriculum would probably be best (leading to students from various houses and grades being in classes together, depending on their preferences).

So, a revised list of classes (none of which are actually considered "core", except for the student's preferred of the Four Arts and maybe Magical Theory, which covers all of them) might look like this: 
-Natural/Classical Arts
-Voodoo Arts
-Shamanism
-Oriental Arts
-Magical Theory
-Alchemy 
-Transfiguration
-Potions
-Charms
-Herbology
-Defense Against the Dark Arts
-History of Sorcery
-Astronomy
-Arithmancy
-Study of Ancient Runes
-Divination
-Magical Flora and Fauna
-possibly more

And each student chooses (with the assistance of academic advisers and their Head of House) a reasonable number to take each year. So, not all students take every class, and some take the classes at different levels, as long as they believe they are able to handle the coursework. Maybe there would be a small number (three? four?) that they take every year, including their preferred of the Four Arts, and the rest are cycled out as they go along.

How does that sound?