Quite. One of Shane's strengths as a character - and this episode is a great example of it - is exposing the whole 'if I was in a zombie apoalypse' logic. A lot of the appeal of the zombie apocalypse fantasy is picturing oneself as the person with the primal amoral will
to survive, doing whatever it takes, and so on. The series kind of exposes this in Shane as basically a kind of sociopathic cowardice.
What makes Shane interesting as a character is despite how low he's sunk, and how naturally this lowness comes to him, he wants
to be the hero. He wants to do good. He wants to believe that his ends justify all his means. He's the same guy who'll beat a man to a pulp for abusing his wife and then try to rape someone else's.
The man is a ticking time bomb, and also one of the best reasons to keep watching the show.
They move because a zombie apocolypse show would be boring without zombies, not because there's any medical explanation that would allow them to do so.
Of course, but the behaviour of zombies by necessity requires one to reasses how we define living or dead. They do behave like living things, that they consistently desire food - that they desire
at all - is a pretty strong practical evidence of that.
So for Hershel to consider the zombies living makes perfect sense. And while it's possible there may be no cure, that can also be said about many illnesses - the response to an incurable illness isn't necessarily to kill your patient. The shed thus was kind of a moral equivalent to a mental hospital, which is no doubt why Hershel brought up the example of schizoprenics - schizoprenics may be dangerous, schizoprenics may never get better, but that doesn't mean you shoot them in the head.
But from what the CDC guy said and what has been show, it is actual death and decomposition.
Not something that Hershel was ever told, however. This was one of the bigger oversights for me in how the group behaved (not that they're known for their foresight or competence).