Great stuff!! - exciting eh? How many eggs were set in total? The chicks can survive for a day or so without water or food, so don't worry about leaving them until tomorrow. You could always gently life the mum up and see what else may be going on (and remove spent egg shells). In my experience...
From my experience, sometimes they do, other times they don't (and I'm talking about the same hen). Maybe its dictated by temperature or possibly experience at being a mum - I'm honestly not sure. Either way, she knows what she is doing but i know from experience that the waiting is a lot...