That's awesome - yes, I much prefer hatching my own backyard flock eggs - and hopefully after this stint of shipped egg hatching, I will have the breeds I want to finally start doing more of that!
My Buffy broody this morning has three chicks and 1 more zipping - so only one egg to go (I didn't get a good look at it, so not sure if it pipped or not.) And then the true test of what kind of mamma she will be!! I wonder when they decide they're done hatching and that it's time to start raising the babies (taking them to water, etc.)
In general, I think mine usually get up fairly quickly after the last one hatches. I've seen little half-wet ones trying to keep up! But it probably depends on the hen, and the whole length of the hatch. Some will stick on the nest as long as there are unhatched eggs. I had one hen that took a big broody poop, right there in the box, so I knew she wasn't going to budge with eggs still under her. Dead ones or not! Others, I think, can sense if eggs are dead, and will leave them. I try to keep water and feed within fairly close reach, so if she wants to stay on the eggs, but wants to point out the food/water to the little ones, she can.
I now have 6 momma hens raising little ones, all under 4 weeks old. 3 of the 6 groups are in one pen (chocolate orpingtons)! They are all helping with their own, and their nieces and nephews. Its been fun to watch.