Here's an article on broody hens
https://www.backyardchickens.com/a/broody-hens
I actually haven't read it, but there is more than one way to manage a broody, like most things chicken.
It's actually best to collect the eggs you plan to have a broody hatch somewhere like your kitchen counter for a few days, up to a week, then remove whatever is under her and place them all at once -- and mark them with a felt tip pen, especially if other hens will have access to her. This way you can put the right eggs back under her and remove newly laid ones each day while she is setting -- so they will all hatch more or less at once, usually all within about 24 hours. The reason is, about a day after the first chicks have hatched, she will abandon the nest to raise the chicks. Then you need to put the rest under another broody or in an incubator, or toss them. Now and then people have had success with things like putting them in a box with a heating pad and a bowl of water for humidity. At least one member hatched a chick or two by keeping the eggs in her bra 24/7.
The number of eggs depends on how many she can cover well, usually between maybe 6 and 12, maybe a few more.
I've had broodies set on eggs and raise chicks in with the flock. The setting in with the flock is a bit of a problem; raising the chicks in with the flock has never been. For the setting I now have a broody room, about a 5'x5' fenced off area in the coop (fenced with chicken wire.) If she sets with the flock, the others steal eggs, add eggs, break eggs, climb into the nest and sometimes cause breakage -- all sorts of uproar. But chicks have been hatching and growing up this way for eons before humans interfered. The only thing is, in nature, the broody usually goes off to hide til the chicks hatch, then leads them to the flock. My neighbor thought for a few weeks that he'd lost a hen, til one day she returned from the woods, marching with several chicks behind her.
After the chicks hatch, the mama should protect them from the rest of the flock. Usually she will attack anyone who gets too close, at least the hens. In my flock, the rooster has either ignored the chicks or helped baby sit and teach. The mama usually "kicks the kids out," returns to the roost (if she hasn't taken the chicks there already) and soon starts laying again, after a month or a bit longer. She will peck at them a bit to make them leave her alone and stop following her. At that point the flock has accepted the presence of the chicks. They still tended to hang out and even sleep together, off by themselves, but there was no trouble between the groups, and eventually the chicks just became part of the group.
You can feed a flock most any of the feeds: starter, grower, flock raiser, if there is oyster shell on the side so the laying hens can get enough calcium. What many say you shouldn't do is feed new chicks layer feed for a few weeks, as the extra calcium can damage their organs. I fed my whole flock grower for well over a year because it had the most protein of the locally available feeds, which still wasn't a lot, I think 16%.
I've never tried to candle an egg, just never bothered. You can learn about it in the Incubating forum. Look in the blue area at the top of any forum, what we call the stickies, for informative threads. I've never had an egg blow up, but maybe I've been lucky. There is good reason to think broodies know when an egg has died; I think they sometimes eat them; I've certainly had a broody eat an egg and hatch the rest. If one does blow up, it contaminates the nest, and you need to remove everything, and clean the other eggs.
You've probably discovered there are lots of other threads on here about hatching with a broody. Most are in Incubating and Hatching Eggs rather than Raising Baby Chicks. Happy hatching!