The ED is 'Hallelujah' by la la larks. Search with keyword 'kuusen' on nyaa in the audio section. It is there.
Fight music? Which fight/episode are you talking about?
For any future songs - nyaa will normally have OPs and EDs of recent animes. If there is a song I can't find anywhere, I go to Youtube and there's a very good chance I'll find it there. I then download it and convert it into audio format.