Continuity mistake: When Bonnie is filming the transformation of the Zygon man who she stripped of control over his shape, her grip on the phone she's using changes between shots.
Continuity mistake: When Bonnie throws the laptop with the Osgoods' message to the floor and stomps on it, the computer's position changes between shots - take note of the tape markings on the floor. In addition, the position of the plastic frame of the laptop's screen changes: in the first shot, it's mostly popped out, but in the second shot, it's mostly attached.
Continuity mistake: When Bonnie gets a video call from the Doctor, her grip on the phone changes between shots.
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.