Can you reset passive skills or is it a one and done type of thing?
You can play with skill and change them anytime you want. But on inferno, sticking with one build is better because of magic find factor that is rising - change it and its back to zero.
So you loose your character if
You die in inferno and while playing hardcore as well?
You'll loose you hardcore character. He is sixfeet deep.
But you can die infinetely on every difficulty.
Thing that matter is hardcore - die and permadead.