The time varies by bird but generally once they are fully feathered Mom kinda starts doing her own thing again.
As far as flock acceptance, depends. They went out of the nest with mom today and one of my older hens challenged mom (over food) but mom went into a crazy mama rage and I had a hen fight on my hands so the other hen is taking a time out in a cage until the babies are a bit older and more sure footed.
Then I watched and saw another young hen pecking at the babies. Mostly curious I think but they weren't moving out of the way so she got another cage until the babies are a little more savvy.
If the broody is a hen that is higher on the pecking order, you have less challenges and issues. I always like to watch them as much as possible the first week to see how the mom and the others are handling it.