Im a new chicken owner who cares very much about what I own and care for, but my arm is being twisted now, when I got my chickens I got three hens two of which died and I got 3 more all supposed to be hens but one wasn't, he was a rooster a white grey americauna/easter egger (don't know exactly...
that's a good tempature for young chicks fresh from the egg but it depends on the age of the chicks because as they get older and grow there adult feathers they don't need as much heat than try used to
check with your state regulations on fowl if any regulations says something against massive birds then it's a no go, and I would advice against it because rheas need plenty of land to move and free range and could easily hop a fence unless it's wings feathers are clipped
if it was broken or fractured she would not be walking or standing at all (I know what it feels like to have a fractured leg), it's most likely bruised or jammed, just keep a careful eye on her, and don't worry one of my growing chicks had been attacked and the outcome much worse than this and...
Today one of my growing chicks about 1 month old died leaving her sister alone with 2 other 2-3 month old chickens, when the smaller chicks were together they ignored the bigger ones, but now that her sister is gone (and with chickens being social creatures) she is alone and still being picked...