Once it’s running you no longer need to make it start… once will suffice.
Looking at the URI supplied, I think that the Avahi warnings listed are not a major problem.
Not having Bonjour is not a problem. It’s not running on either of my computers and yet it works fine, appearing and listening in both iTunes on Mac and Amarok on Linux.
I don’t know about the issues with your web configuration. I would suggest that you give up on that for the moment and use the supplied /etc/mt-daapd.conf to configure it, which might also help with your password issues, since that’s specified in that file. If you installed from a package, it should have placed the example configuration file there for you. If you did a source install, copy it out of contrib/.