It's legal to have it mounted and playing music, not legal to skip a song.
If you want to change tracks, you need to pull over where safe and legal, put your hazards on, put your high-visibility vest on, helmet, earplugs and steel toed boots, get out of the car, place traffic cones around the car, then change tracks.
You are allowed to press one single button to answer a hands-free call. I don't think you're allowed to mute the ringer if you don't want to take said call. You must sit there with it distracting you with its ringing.