is my hen broody?

i’ve been concerned about my hen. she hasn’t left the coop for more than an hour for the last 2 days. i’ve handled her, checked her over for injury or illness and she’s completely fine otherwise. i collected eggs today and she growled(?) at me which isn’t uncommon for her if i disturb her while she’s laying. i haven’t gotten an egg from her in 2 or 3 days, she’s my only blue egg layer.

i just went out to check on her and sure enough she’s got an egg (not hers) tucked up under her. she puffs up and makes noise at me for even opening the lid to the coop.

my other question; if she is broody; can i sneak my eight 4 week old chicks under her for her to raise? i have a flock with one rooster and 8 hens (i know, bad ratio but its why i got more hens). will the others be mean to the chicks if i can go about it this way? i have no issue raising the chicks in a brooder but this would be fairly easier for all involved if i could.

i should note that she will not let the rooster breed her and hasn’t for the last couple days. she will not crouch when he makes his advances and just walks away from him? i’ve never had a hen go broody, so i don’t really know what to expect and if its not the case i want to make sure she gets proper treatment if she is sick. she’s my favorite hen.

TIA!