Although I'm a huge fan of Ben Kweller, I don't think I'd cover one of his songs, simply because there's just so much of my own stuff I wanna do.
I approach writing female characters the same why I approach writing male characters. I never think I'm writing about women, I think I'm writing about one woman, one person. And I try to imagine what she is like, and endow her with a lot of my own thoughts and history.