*****spoilers*****
John Hurt is most likely the one who fought the time war. if you notice whenever the time war is talked about the doctor never takes full blame of it, this is why. It wasn’t him who killed his whole race it was the John Hurt doctor. Is this why all the past doctors are running away from when Clara is in the Doctor’s time stream? do all of the previous doctors shun him for his actions
As for Clara being River song, I highly doubt it. Yes they are similar characters, but if they were the same person then wouldn’t Clara know it? im not sure.this just my opinion