They are installer cache files. CC3+ doesn't need them at all, but installer operations (uninstall/repair) may complain because it can't find the caches source files needed for the operation.

May it be that you are just confused by the Edit Properties box? The properties shown there ARE NOT the current properties of the entity selected, but rather the currently set properties on the status bar. It can be a bit confusing at first that it behaves that way, but it is much more friendly when you start working with multiple entities at once, and you are also much more likely to need to change properties to the current status bar settings rather than inspect existing settings.

To see what sheet an entity is actually on, use the Info -> List command on it.

No. While Cosmographer allows you do draw star systems, it is a manual process. It has no concept of things like orbits and calculating positions or the effect of bodies on each other.

Your pink poly is on the SYMBOLS sheet, and there are no color key effect on that sheet.

Note that if you use the image function instead of the attach function when uploading them, you can also get the images to show directly in the forum post.