as for mirrors…when youre an onen your primary concern is the burial of the mes which is why you dont make brochos when you eat…so the mirrors are quite secondary and only apply once youre an avel.
as for music…why would you be an onen long enough? but to answer your question im almost positive that the halachos of availus only apply once the body is buried (or at least after the funeral). as for music to help you fall asleep after the burial…you need to ask your rav about that. everyone is different.