I don't know if I got you straight, but about the type A, B, C, D it is not about how the boss attacks, but it's how your bullets are going to attack the boss.
about the final boss it will still have the same hp and same phase. When it changes phases, it becomes a little transparent, spins, gives enough time to let the attacks of the old phases go away so that .(Actually it does exactly the same in current version)
And about your suggestions, I just considered that and thought that may be good : I worried that my current plan may make people avoid selecting B, and you gave me a solution for it.
Since I'm working on my new fangame, so I'm not confident that the 1.5 version will ever appear. And if next version appears, that will be the final, so if you come up with more, tell me as soon as you can.