Hi Thomas. Glad to hear of your interest in these wonderful machines. I hope we can answer some or all of your questions.
I think the first thing you should do is visit one or more of the booths in Paris to see for yourself what the camera, the paper, and the development system look like. Get in touch with Igor at La Joyeuse and Eddy at Fotoautomat France and I'm sure you can arrange to see the inside of the machine when they're doing their maintenance.
To answer your simplest question first, you're right, there is no negative involved in the process. Beyond that, we can explain using photos and manuals and the rest, but seeing the mechanism working in person is the best way to get a good understanding of the process.
Check out this video that Tim made of one of his machines at work for a taste of what goes on.