If the chick did not move when you opened it, it had died. I am positive you would have known when you broke it open if the chick were alive. Now, be happy with the four wonderful chicks that hatched!
The chicks should be strong enough, now, to leave the nest. If the nest is off the ground/floor or in a nest where the chicks can not exit easily, make a simple nest on the floor, move the chicks into it, followed by the broody hen. If you have other chickens present, move the new family to...
When candling, if the border between the air cell and chick forms a distinct line/edge the chick may still be alive. If that edge is fuzzy, faded, or blurred the chick has died. If unsure put the eggs under the hen until tomorrow and candle them again. The air cell membrane deteriorates rapidly...
Yes. It is not out of the question for eggs to hatch late. If you know how to candle and have experience doing so, a quick candling will tell you if they are alive. Also, by now, you should hear tapping/peeping when the egg is held to the ear. If nothing is heard they probably won't hatch.
There is no exact amount of time between pipping and actual hatching, but roughly 12 hours. I also had eggs pipped last night and they still haven't hatched, so these are beyond 12 hours. Be patient and try not to disturb the nest; disturbing/looking in the nest could cause the eggs to die in...