I hate to blow holes in a couple of these theories, but HOW can Susan be related to Ruby or Belinda if she was left by the first Doctor in Earth's future, therefore, there's no way she could be related to either one, unless Susan managed to go back in time herself somehow, that the Dalek Invasion Of Earth was set in 2164 if I correctly, so you're talking about 140 years difference as we and the current season is set in 2025

It All makes sense, Doomsday beat Superman so bad that Clark was in a deep deathlike coma, yet some people forget that, so, yeah, definitely he should feel pain in the healing process, perhaps enough pain that he es out a few times, but it is a necessary scene, please keep it in there

Actually Nightcrawler and Apocalypse logically lend themselves to this idea, but I am surprised at the omission of Illanya, as she's another one at would be an obvious choice