RE: Wilf and Donna
I'm of two minds on Wilf...he was shielded inside that chamber which is what kept him from changing into the Master...but then, there must be something up with him that allowed him to actually remember the bad dreams. I'd be pleasantly surprised if he turned out to be an arched Time Lord hiding out on Earth, but I'm not holding my breath.
As for Donna, if her mind is half-human and half-Time Lord, with the Time Lord portion being suppressed, I wonder if somehow she's now fully Time Lord, with the human half being transformed into Time Lord by the Immortality Gate? Maybe the Doctor will have some help on the "outside" thanks to the Doctor Donna? If that's the case though, I don't see her staying Time Lord at the end though...maybe the Gate can somehow heal her while allowing her to retain her memories of the Doctor?
EDIT: Yeah, apparently
Happy Day Riot had the exact same thoughts at the same time as I did...