Regardless of their race, anyone not familiar with what goes on at a Pow-Wow is not going to be aware of the things that go on there.
There are people Black and White who claim to be Indian,and go to Pow-Wows all dressed up in Indian themed T-shirts, Minnetonka mocs and headbands with turkey feathers thinking that they can compete. And they cannot, why? Because they're not dressed appropriately (sp), and recieve stares, and they take that for racism. Sometimes it is, but most times it isn't.
As far as your friend getting her hair and nails done to go to a pow-wow, go ahead and let her. Just explain to her that she's there to watch and learn, no to dance. Once she's familiar with her nation and their regalia and dance styles, perhaps one day she can get out there with the best of them. Otherwise, just get her a shawl and go out on intertribals or a round dance, if she feels such a need to be involved.