I noticed something which may have been a big clue. The music that played when the woman uncovered her face and the Doctor recognized her was the same music, incl. tone etc, used when Donna initiated the meta-crisis, which to me fits with Donna being the woman in White.
As to the other person, I'm not sure, and this is stretching it, but what if Wilf actually was on Earth with a 'fob watch'..as a human, planted to deal with this situation? That would make Donna part time lord, perhaps latently, which only showed up when triggered by the metacrisis. Perhaps Wilf in some other regeneration was the other unseen time lord?
To stretch it even further, what if Donna was indeed the Doctor's mother? (time is not linear for time lords, after all!) As human, he wouldn't have recognized her, and it would fit with the fact that Donna had NO romantic interest in the Doctor at all....there used to be theories floating around that suggested the Doctor was part human, which explained his affinity for humanity.