Regarding Ace, she was one of Fenrick's Wolves. Fenrick was the uber space vampire being that the 7th Doctor had as his main recurring villain. That story line was never fully realized due to the cancellation of the classic series. In ancient Time Lord lore, the space vampires were their major adversaries in the First Time War, if memory serves. Before Fenrick, the last time they were seen in the series was during the NSpace series during the fourth Doctor's run and the episode with the giant space god suggested at one point that it was in fact a sleeping space vampire, but that is a bit of a reach perhaps.
If the whole Clara thing is Time Lord related, there are plenty of old options for that, but I kind of doubt they will be used. Romana and the Rani are both female time lords from the classic series who were likely not on Gallifrey (Romana being trapped in NSpace and the Rani being a renegade), plus there was the genetically crafted one from the Doctor's Daughter episode during the Tennant run. The Doctor's Wife more or less established that there could be Time Lords that are hiding outside the main universe, as well, if Moffat just wanted to pull a made up one out of his ass for the Clara plot. I hope its something that can be tied into the Time Lord lore, at least. Its too bad that End of Time basically shut the door on Gallifrey ever returning, because it would be nice if the show reverted to more low key stories instead of him having to personally save the universe on a regular basis and it would allow for the Daleks to return in a more reasonable capacity as a sort of stalemate opponent to them. Oh well, it looks like we are going to get the "Doctor is the Other" storyline officially made into cannon, which is where they were headed with the 7th Doctor.