The software is 32-bit, so it can't address more than 4GB of memory, which it should do by default.

That said, the rendering is CPU-bound, so unless you are manually forcing it to always use very high quality textures in the display speed dialog (a rather bad idea btw, since it won't affect visual quality, CC3+ automatically uses the right textures based on the current zoom level, manually overriding it just eats performance with no benefit) so the rendering speed is mainly limited by CPU-speed (Actual clock speed is the most important here, not the number of cores) .

Note that since CC3+ is a vector-based program, it will need to re-render your display every time you change view, it is not a finished bitmap just laying ready in memory as with regular image editors. The amount of work needed here depends a lot on your display size, for example a 4K display is 4 times as many pixels as as 1080p one, so it will also be 4 times as slow in that case.

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.