Figured out the music thing:
CyanogenMod-4.2.8 | CyanogenMod
"For the mysterious music fix – it looks like the system audio files get removed during the flash process. With no audio, the system plays music files for notifications.
Download the audio resources from Cyanogen’s website and install to the SD card to remedy."
However, my phone has been going slowly for a while, and not just since the 4.2.8 update. Can someone help me out?