Good cut, allthough I wouldn't use feather. As you can see, it can make your edges (especially on the hair) rather blurry
Yeah, feather can be tempting to do on hair. The problem is that it will always take some of the background with it and it will make it blurry. I try to create several layers of the hair composed of several different cuts.
in regards to feathering, all i would do is just contract the selection of hair by 2 pxls and feather by 1. then it should result in less background showing up.