Unfortunately the answer is: it depends.
Some people have good luck leaving the broody hen in the main coop, others isolate her.
Some people find that their adult chickens attack the new chicks, others don't.
Some people's other hens try to lay their eggs in with the broody, others don't.
I have my first broody and I'm having some fertile eggs sent for arrival tomorrow or next day, so I'm in your same boat.
I'm not planning to isolate her or the chicks. If she puffs up and hisses at the other chickens the way she's doing it to me right now, she will scare the bejeebers out of them anyway, and none will dare to touch her chicks.
Do mark the fertile eggs you put in with a crayon or something. Then you'll be able to pull out any "extras" that mysteriously show up from other hens.
Good luck.
And what the heck is a shark cage? I know there's big sharks in South Africa and all...