Somehow managed to avoid spoilers until I could watch it last night.
FWIW they handled the death of a baby similarly in season 1, just a bloody car-seat they found when leaving Atlanta. I think someone grabbed her on the way out but the one thing I've learned about this show is to not to apply the normal TV show rules to it, anyone can die at anytime.
It was Hershel's time to go, he fulfilled his role as Rick's mentor and he'd turn into a burden while their on the move. Not killing him would be a pretty ****** way to handle a great character.
I don't think the governor's adopted daughter's death had any effect on him whatsoever. IMO he wanted to want redemption and his adopted family was a tool for that. In the end he reverted back to the governor and decided his ego was more important than anything.