Have you ever tried oatmeal baths?  I've never tried it on ferrets, but
it worked great for my kids when they itched.  Also, they problem may be
dry skin, so you could add some more fat to her diet.
 
As for the biting, love, patience and consistency will help.  I scruff my
guys and "GENTLY" hold their jaws closed with thumb and forefinger while
telling firmly "NO".  It has worked for old and young, so far.  It did
take me three full days to get Little Bit to quit, and she would still
occasionally grab me, but for the most part she quit.
 
Hope this helps,
Shelley
[Posted in FML issue 4425]