My broody hen won't protect them?
Mine always protect their chicks. I typically raise three or four broods with broody hens every year and have never lost a chick to another adult. Some people have. The problem with dealing with living animals is that anything can possibly happen. You just don't get guarantees one way or the other.
Do I need to isolate her with the eggs or chicks if they hatch?
I let my hens incubate with the flock, hatch with the flock, and raise their chicks with the flock. Some people isolate the broody and eggs/chicks in any or all of these phases. We all do these things differently for our own reasons. I don't consider my way right with every other way wrong, I look at it as we do things differently.
Will the other chicken bother her eggs when she leaves to eat, drink and poop?
Sometimes another hen will get in the nest to lay an egg when the broody is off the nest. Sometimes the other hen might join the broody in the nest to lay an egg, mine often do that. Some broody hens will keep other hens from joining her in the nest but most of mine share the nest without a fuss.
There are two risks with this. If the broody hen does not want the other hen to get on the nest and lay an egg while she is on the nest she may fight to keep her off. Eggs may be broken in that fight. I personally have never had that happen but a few people on this forum say they have. Sometimes if another hen is on the nest when the broody returns from her daily constitutional the broody may return to the wrong nest. I've had this happen a few times, not many. I put the broody back on her nest when this happens and I've still got good hatches, even when the eggs feel really cold. It's not a good thing to happen but so far it has not compromised any of my hatches.
Will they attack the chicks? The broody is 2nd to the top in pecking order and I had read that was a factor.
M broody hens have always protected their chicks, no mater where they are in the pecking order. Others I trust say they have had hens to not protect their chicks. My dominant rooster has never threatened chicks but you don't have one so that doesn't matter.
My hens don't go out of their way to threaten the chicks though again some people say they have had hens do that. You just can't tell what will happen with living animals. If a chick leaves Mama's protection and invades the personal space of another hen it may get pecked. Often it will. One thing I've seen several times, usually when the chicks are about two weeks old. A chick leaves Mama' protection and goes to stand with other hens as they are eating out of the feeder. The other hens might leave he chick alone but usually it doesn't take long for one of those hens to peck that chick. The chick then goes running back to Mama as fast as its little legs can move it, wings flapping and chirping for all the world to hear. Mama typically ignores this, the chick has learned that it is bad chicken etiquette to bother its social betters. But if a hen follows that chick to teach it a further lesson Mama whips butt. Nobody threatens her babies.
You have several others that are not grown hens. Those can be a threat to the chicks too, maybe worse than the adult hens. But since they are immature Mama can easily scare them. I often have different aged juveniles in the flock, Mama has always been able to manage.
Now it's time for my warning. What you do not want is for the chicks to get somewhere Mama can't protect them. If that happens they are in danger from the other hens or juveniles. If your chicks can get in with those 5-week-olds and Mama cannot get in there, the chicks are in danger. I lost one once with 8-week-olds because of that. My fault, a baby chick could get through the gate. If you try to isolate the broody and her chicks and the chicks can get out of that enclosure they are in danger. If you try to isolate make sure you isolate.
The more room your broody has to work with the easier she has it. That's in the coop and outside both. From reading your posts I'm not comfortable you have a lot of room. My coop is 8' x 12' and I have over 3,000 square feet outside for them to use. I think that is a big reason I don't have problems. You don't have as many chickens as I do, which factors into space requirements. A lack of space can cause integration issues too. If your room is limited that might be a god reason to isolate the broody. But if room is limited integration later may be an issue.
Good luck, however you choose to go forward.
