But in any case, when I open a the project and see a line of "versions."
And it seems every time I "open" the master, or one of the versions, another version is created and now resides in the every lengthening string of versions.
That will depend on your Aperture preferences: You probably enabled "Aperture > Preferences > Advanced > Create new versions when making adjustments"
You can disable it in the "Advanced" tab of the preferences.
I don't know what was done, if anything, to any version.
This you can see in the "Adjustment" tab of the "Inspector" panel, when you select an image. All adjustments, that have been added to a version, will be highlighted.
For example, the checkmark to the left of the "Highlight & Shadows" brick will tell you exactly, that the selected image has "Highlight & Shadows" adjustments, but there are no "Levels" or "Curves".
What I am doing: I disabled the option "Create new versions when making adjustments". When I want two versions of an image, for example a cropped section in addition to the full version, I create it "Photos > Duplicate version" and name it immediately. as you probably know, versions created by editing in Aperture will not take up much space; they do not create additional original image files, only preview images, if you enable the sharing of previews. So you can have as many versions as you like. you may want to stack them to get them out of the way. There is an option to do that automatically.
Versions created in an external editor (e.g. Photoshop) are treated differently. They are not really versions, since they have a quasi-master, a new original image file (pds or tiff), and you cannot undo the edits. After an external edit you really have two separate images with own original image files. I try to avoid the external editors, if a task can be done in Aperture without jumping through hoops.
How raw images are treated will be determined when importing them. They may have two original image files, if you import them as raw+jpeg, or only a raw original.
For raw+jpeg pairs you can switch between the raw and the jpeg as original. I rarely import pairs. If I want in-camera processing or use an unsupported camera, I import jpeg, and in all other cases raw only.
Have you seen the excellent online version of the Aperture user manual?
Leoni, thank you very much. This solved both parts of my problem: why all the versions and what's been done to them. In the former, I jumped in and set a preference without understanding the implications; in the latter the answer was right in front of me and I didn't see it. So thanks wrapping it all together, plus the RAW export info that I still have to process.