First off, amazing episode.
I think the Doctor is going to be far more brash than 10 or 11, but he will try to rid himself of the thing that drove the previous Doctors: hate.
Also, does anyone else get an older brother/younger sister vibe from the Doctor and Clara? Zero romance, but tons of witty back-and-forth. The Doctor won’t like Danny either, which adds to that.
Lastly, as of now I’m sticking to my original Missy theory, but I also find the Rani theory to have some backing. It’s nearly impossible to peg her.