I can't reply to this until you realize that clam Genjutsu isn't just going to make mirages of the Mizukage.
The Mizukage and his clam aren't connected in any way bar the fact that he summoned it yet it still makes mirages of him, because he wants it to. The same way its going to make mirages of the Raikage and Mu, because they do it. Its a Genjutsu under their control and there is absolutely no reason why they can't make illusions of Raikage and Mu in their own illusion. It not being shown isn't a legit way to contest this. The only way that your stance would make sense is if the Mizukage was somehow linked to his clam in some way, but as far as we know, its just a summoning.
Yeah, except he got Senju DNA after his fight with Hashirama, moot point.
Ok? Was he Perfect Jin at any point during his life though? No, so Alive Minato doesn't get Bijuu Mode. That is as simple as its going to get.