Re: Wanda or Vision, who should turn up first?
If/when the Maximoffs appear in the MCU, they *won't* be mutants, rest assured. Feige has already said that the contract with Fox won't allow that. But he said they *can* appear in the Avengers, in their classic form, before the Magneto family tree was added by 1970s writers.
Personally, I'd prefer they stick to canon, and give us Scarlet Witch and Quicksilver first, Ultron next, then Vision.
THE COTTON AVENGERS
...They move like slick cotton on oil.