I still find the idea of Tsukune training weird :/ I especially find it weird to think he's that special. He's just one guy, why should he get extra attention? I actually also have trouble imagining Dante doing any actual teaching. When I say teacher, I mean "teacher" like Wolverine in X-men. "What do you teach, Mr. Logan?" "....Art." Basically, teaching's a cover for something else, like protecting the place or whatever.The manga works if you ignore the common sense.
So the plan is for tsukune to train under Dante and then for Nero to join the cast for season two.
I think Ao no exorcist would work as well as Bleach.
I actually haven't watched Ao no Exorcist yet, but I hear it's good. It would be an interesting crossover. If I remember correctly, they have lots of hybrids (just not from Satan himself). You would have to reconcile the different structures of their demon worlds though.