I never had any trouble seeing with the rear view mirrors, and didn't remove any rear headrests. The middle one is set lower, so full view to the rear there. I don't think it is any different than most other cars in that respect, certainly not any that I have owned.
Yup, get the red one, makes for a very pretty car. Just be ready for all the attention you will get. And cops might not be as gracious with letting you off if caught speeding. And safer, too, in that other cars can't miss seeing you in roundabouts and when changing lanes. When I had my light blue Crosstrek, can't count the number of times people have inadvertently pulled out in front of me. Wife said the same thing. Had to watch other cars like a hawk, not always knowing whether they see you or not. Has yet to happen with the I6. My Solterra is grey, and has happened with it, too.