Incorrect. See previous argument.
Understood. He's a Master of the Mystic Arts who became comfortable with an Infinity Stone despite just getting it and with the Third Eye and Dark Magic already has experience.
No, I've made it clear this is my opinion because you have not provided sufficient evidence that the on-screen evidence doesn't work with the official placement.
Maybe, but the book is out and it provides official word. It remains official until proven otherwise, not "could be wrong" until proven right