Ok I actually think I got it working!! 
Ran mopidy deps and got “Status: deinstall ok config-files” (which I couldn’t find any usable info on). Followed up with dpkg --list, and saw that Mopidy was RC (which I found out means not installed). Tried to reinstall with sudo aptitude reinstall mopidy and sudo apt-get install --reinstall mopidy, but it wasn’t found. Looked in the guide to install mopidy, and used the following commands:
wget -q -O - https://apt.mopidy.com/mopidy.gpg | sudo apt-key add -
sudo wget -q -O /etc/apt/sources.list.d/mopidy.list https://apt.mopidy.com/wheezy.list (figured it would be a mistake to use the jessie.list).
After running sudo apt-get update and sudo apt-get install mopidy, and rebooting, lo and behold: MusicBox runs as a service and I can even use AirPlay!! 
Next step is making a backup image and try restarting Deluge from terminal. If this works, I’ll try running Deluge as a service from boot. Wish me luck!