Lots of questions and pretty good ones. Hens have been hatching and raising chicks with the flock for thousands of years without any real help from humans. They know what to do instinctively. Don’t worry about turning the eggs or really doing anything else. The hen has you covered.
Eggs and hens come in different sizes. A bantam might have trouble covering 4 regular sized eggs. So the right answer depends on the size of the eggs and the hen. The hen needs to be able to completely cover the eggs. I’d suggest leaving her a bit of spare space too. Other hens often like laying with a broody so it’s good to have a bit of extra room. I normally give a hen 12 eggs of the size she normally lays. I have given 15 and she did fine. When I was a kid on a farm many decades ago, a broody hid a nest and brought 18 chicks off the nest with her. I never did find her nest so I don’t know how many eggs she had. They can handle more, depending on size, but to me 12 is a good number.
I don’t know what hens you have, but I suggest you get a rooster from a breed that is equivalent size. A bantam rooster could breed a regular sized hen. A really large rooster could breed a much smaller hen. But you could have issues with either one. You’re better off getting a rooster from an equivalent sized breed. Any rooster will try to mate any hen of any breed. That’s not an issue.
We all do different things when it comes to broody hens. I let mine hatch and raise them with the flock. Some people isolate the broody, either when she is setting and hatching or when she is raising the chicks, or both. There are many variations of this and we all have unique conditions. There is no right way or wrong way. It’s pretty much the way we choose to do it in our unique situations with our unique experiences. You can have problems both ways but it usually goes really well. It’s still stressful but it usually goes well.
There are a few things that are consistent. Gather all the eggs you want her to hatch and start them at the same time. Very important to start them at the same time. I suggest marking them so you know which ones belong so you can remove any new ones that show up.
If you let her hatch with the flock, check under her daily, after the others have all laid, and remove any eggs that show up under her. As long as you collect hem daily, they are still good to eat. That’s basically all I do, just leave everything else to the hen. I’ll let others tell you how they isolate them.
Good luck!
