Most of the eggs should hatch on the 21st day of incubation. However, there may be a few stragglers that hatch over the next day or so.
I would keep the hen and chicks separate from the flock until the chicks are older. Otherwise, the other birds may attack and harm the chicks.
Most hens make excellent mothers, and don't need much help from humans. One possible concern, though, is predator protection. Hens don't always choose the safest places to make their nests, and a broody hen is a sitting duck. Is the area she is in within a fenced area? If not, I would try to...