It sounds like he's gonna be a combo of Hartnell-Eccleston, less obviously friendly Doctor. At least, thats kind of what I got from this.
Nah, Eccleston was friendly enough, I rewatched his entire season this year.
"Difficult" to a "fierce" degree, to the point where you're thankful for the normal characters, really points to Colin Baker, who obviously drew some from Hartnell.
Why do I get the feeling that we're at the point where Davison just regenerated and we had no idea what was going to hit us. Clara may be the next Peri.