Looking at the Army Special Rules page in the Vampire Counts book, it states that the army general must be a wizard and if he is able to choose a lore, he must use the Lore of Vampires. What happens if you give a Vampire Lord the Wizarding Hat enchanted item. He can no longer choose the Lore of Vampires? Does he "have" to select a lore randomly from the army book? It seems like a grey area. I would assume you could no longer use Vampires, as the item would override it and force you to choose from a random lore.
Even more confusing is if you used the Wizarding Hat with Forbidden Lore.
If he was treated as a level 2 wizard because of the hat, could you still buy an additional magic level, I don't see anywhere it says you cant and there's nothing in the FAQ.