Keep an eye on the others (see if the bad habit has spread - kind of like egg eaters spoiling the flock). If it is just the one girl you'll need to keep her seperated until the others have healed (don't know about successful reintegration, either).
If it is impossible to seperate: Try the...
The naked backs are probably a result of your roo at work (a heavy grit emery board to round of spur tips and claws will mediate the damage - this is usually less of an issue as they get older).
a spray bottle filled with a 50/50 of betadine/boiled water (betadine tea) can be used to clean the...