Deep Breath - S8-E1
Trivia: In the scene at the end where Clara gets a phone call from the Eleventh Doctor, the shots with Matt Smith were filmed during the production of "The Time of the Doctor", almost a year before "Deep Breath" was made.
Deep Breath - S8-E1
Trivia: The Clockwork Droids that serve as the episode's villains came from the SS Marie Antoinette, a sister ship to the SS Madame de Pompadour from "The Girl in the Fireplace". It's not surprising that the Doctor finds the situation familiar. The fact that he doesn't recognize the name of the ship is also unsurprising - he never found out what the Madame de Pompadour was actually called in the previous episode.
Deep Breath - S8-E1
Trivia: The face that the Doctor wears when he disguises himself as a clockwork droid was cast from the statue of the Eleventh Doctor at the Doctor Who Experience. This is especially noticeable when he's pulling the face off.
Chosen answer: 1) When Stephen Moffat took over he ignored a lot of what had been developed before (there is not in-universe answer). 2) It would have killed Rose, so the Doctor absorbed the energy. His body regenerated before the energy could do a significant amount of damage that would prevent regeneration.