I don't believe the seraphon allegiance ability counts as a move.
I don't think this is the case. The balewind and the wizard riding it are treated as a single model after you cast Balewind.You are correct. It does not count as movement. Technically you can teleport a Slann on Balewind without losing the Balewind. As the Balewind states it is consider part of the model. This might be errated to say that models on a Balewind cannot move of be removed and replaced on the table while on a Balewind Vortex.
I don't think this is the case. The balewind and the wizard riding it are treated as a single model after you cast Balewind.
How is it legal? They are treated as a single model, so you can't teleport off it because you would teleport the Vortex along with you.You definitely can do it. I have done it at tournaments. They might errata it away, but for now it is legal.