That is true. And if you think about it, in the game you unlock the rasengan at a level where naruto is supposed to be in shippuden state. This is also prior to konohamaru knowing it, so you inference that Naruto taught Breeze the rasengan.

That is true, though Naruto still has the ability to teach someone, is is more unlikely. As for your theory, i find it to be quite interesting and can possibly be correct. Each main being one person, would explain the change class option. Though, the one thing I do wonder is that this character was created by orochimaru. In what appears to be lots and lots of them too. So you can suppose he was making an army for his bidding. This is when I pose the question, if this is what he intended, why not just make a superwarrior with all DNA of the mains in one personality rather then 5?