I'd say there's no clear definition of OWK's personality being prim and proper, or a bit of a maverick, in the PT... The OT, he's tough to gauge, and what happens between is left to go yet, but I got the feeling from his E1 final scenes that he was a little Qui-Gon-ish in behavior... Yoda even references it as something he doesn't think Obi needs.
In ROTS he confides information in Anakin that maybe the Council didn't want explicitly said to Ani... At least I got the impression that was the case. The whole, "We want you to spy on Palps" bit. He reacted to Anakin by basically telling him he agreed with him on the matter, but it was what the council ultimately wanted... It almost seemed to me like Obi caved and just told Anakin the whole thing rather than try manipulating the situation. Bad move ultimately.
Certainly doesn't make him off the wall crazy or anything though.
I could see the mixed-race 20-something being an unknown offspring of Mace too, and considering Windu's ultimate popularity from the PT, he'd be one of few things I think most fans wouldn't mind seeing making an appearance. Lando makes sense too since barely anything's even mentioned about him. He doesn't seem to have even been asked to be back on board for this which is kind of insulting. He's maybe not AS important as the other 3, or even Chewie and the droids, but he's still someone I feel should make the cut. Plus Williams doesn't look bad for his age. He could do it I think.
I wonder if Jeremy Bulloch works his way in again? Or Warwick Davis?
Anyway, I'm still just on this roller coaster hoping it's good and not really caring if it isn't great. TPM has soured me on expectations.