Anyone else care to add to this discussion?
All good questions. If you ever solve them, there'll be more to follow, because of the spectrum of disc golf courses people install, permanently or temporarily, and the ever-changing nature of some of them.
Crooked Creek Park (Chapin, SC), has an 18-hole layout. They added an extra set of 9 holes, in a string, not a loop. Someone listed them separately on this site as the "Pro 9", or somesuch. But nobody plays them as a separate course, since they don't make a loop. I count it all as one course.
Stoney Hill has both continuously evolved, so that few holes now are the same as they were in 2008; and increasingly built two overlapping layouts, so that, at this point, they play as almost completely different courses, with only 4 shared holes. But they're contained in the same footprint, more or less, and I count them as one.
Gran Canyon existed as a private course for years. It was then closed for about 6 years, and has since re-opened as an annual temp course. Except the new version is almost completely different, in many places fairways are reversed. I count them as separate courses (in part, to keep my internal debate going as to which was better).
Someone could argue the opposite, in all 3 cases, and have valid points.
A friend built a 9-hole private course, strictly a personal course, so it doesn't even have a name. Can't put it on an official list, but I count it.
Who knows what someone else will come up with, that doesn't fit categorization.
As for the object courses, you'll might want to sort out some groundrules about how long they've existed with essentially the same layout, whether they've had printed maps, etc. You might find some college students with Frisbees have created bunches of them, that each disappear after the term, to be left for the next term to create their own new course.