Simplest is probably just to copy over the ones from the existing symbol catalogs. If you make sure to have snap on both when picking the origin point for the copy, as well as when you paste it into the destination, it is easy to place it in the precise correct location.

Nice map, but the background repetition steals a bit from it. I would have tried either changing the scale of the background fill, or replace it with something that isn't so noisy, or maybe fade it out a bit (can be done by placing a polygon on top with one of the solid xx fills)

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.

Also note that the Shaded Polygon command changes the fill style to whatever is currently selected. You can use :CC2KEEP: to set the current settings to match that of your poly before running the command. Or you can use the Shaded Polygon (Angle by Edge) command which doesn't do this, and at the same time figures out the correct angle for you.

That should work fine. Make sure that you include the System subdirectory of the CC3+ data directory, as this is where all the settings for the symbol catalog settings, master filters and drawing tools are stored.

Note that symbol catalog settings can also usually be fixed manually quite quickly unless you have a lot of them with problems. The most common issue is the file name of the actual catalog being removed from the setting, but the name of the setting itself should be enough to identify which catalog it needs, so you can browse to it and then save the catalog.

It's an advanced topic, not covered in the manual.

It's described in the help files accompanying the program, and also in the Tome if you own that.

When you import symbols using Symbols -> Import pngs... it will do a folder at a time (note that it does not do subfolders, only the content of the folder you point it to)

Are you looking in the right tab of the fill style dialog? If you see "Solid 10", that indicates you are looking at the "bitmap files" tab of the fill style dialog, while "Solid" is on the "Brush Patterns" tab.

Unfortunately not. A workaround is to access the system menu from the icon in the top left of the window and pick the save to clipboard option. Then you can paste it into your editor of choice and zoom in/enlarge it.

I seem to be able to reliably crash it. Did some testing, and seems to be down to building 20. It is right outside the area, but to avoid weird effect clipping at the edges, the render works with a slightly larger area than you select for the export.

Delete the building, and the export should go through. (You'll probably want to redraw it of course, but it is good just testing export once before that to make sure the problem is gone for you)