Will they hatch? Well that depends on wether your hens have had the attention of a fertile roo and wether your broody is a determined sitter. Some hens will get bored and give up part way through, abandoning their eggs to return to the flock. You can encourage her to stay by seperating her into a broody pen, keeping the others out of her space and not disturbing her more than you have to but you cannot force a hen to sit on eggs if she doesn't want to.
But if she stays put, let her do exactly what nature designed her to do. If she is a dedicated broody, she should do it all without your interference. Just make sure she has access to food and water at all times and keep the other girls out of her way so she can sit in peace. Keep an eye to make sure she is feeding....though she may only do this once a day for a few minutes before returning to her eggs. If she doesn't, just lift her off them and put her next to the food.
She will also do one huge, offensive smelling, usually quite wet 'broody poop' at this time...it is very unpleasant and best cleaned from the area.
Once the chicks are hatched, again, assuming she is a dedicated mom, she will do all the necessary caring. They will need chick crumbles opposed to pellets and I personally let her eat them too but also provide a feeder of pellets hung up where the chicks can't reach them. She will teach them how to forage, drink, eat, catch bugs etc while you get to watch. She will also fiercely protect them from the other members of her flock but keep an eye out as they are capable of killing the chicks.....as are rats, raccoons, birds of prey etc.
I always let my broodies rear their little ones in a seperate pen within the main pen so that they are seen and recognised but not actually integrated until they are old enough to stand up for themselves a bit....but lots of people allow them to be reared alongside other coop-mates, it's a matter of choice.
Good luck and let us know how it goes x
