Yeah, she seems to be handling it well- but it's technically illegal if you're not a licensed rehabber.
So I suggest you find one and give it to them...
They can give you lots of advice here, along with licensed rehabbers if you need them- there are many dedicated squirrel rehabbers on this site:
http://www.thesquirrelboard.com
And if she plans on keeping it for longer, I advise trying to find some zoologic 33/40 formula to feed it, and try to give like 3:1/2:1 portions...
And...I don't know the exact things about the squirrel, so I suppose I can't help further, but the people at the squirrel board can help immensely if you provide details.
Good luck! Thank your friend for taking the little squirrel in for me. ^^