For the finger print scanner, just go back into the security settings and re-set it back up. It should have carried over, but sometimes those settings drop.
For the Music player cutting out, open the stock Task Manager app (in the app drawer) and verify that the MUSIC app, the GALLERY app and any other music app you might be using are NOT on the "Auto Kill" list.
There is some dependent resources linked to the GALLERY app that is needed for the media players. So, if it's getting killed, it kills the music. If you ask me, someone screwed up setting those dependencies!
On a side note, I also recommend Power Amp for the media player. It's a $5 app, but you can download a 2 week trial. It's the best media player I've ever used on a mobile device!!!!