Those lines reminds me of the TCP 3-way handshake.

They are meant to be stairs, right? Perhaps making them with some steps and not just lines?

I was also thinking, since this is a cross section, and that hole in the middle still have a backing somewhere, perhaps apply a faded out version of the hatching as a background (perhaps with a tunnel for the stairs?)

And filling the sides with hatching did look much better than just edging it.

Considering that this is a side view, I would probably try out filling the area with hatching. It just doesn't work the same to just have edge-hatching as it does on overhead maps.

Use Draw -> Hex or Square Overlay

Note that CC3+ doesn't allow automatic creation of grids with variable thickness. You could either make two grids, or, since it sounds like you won't have that many whole-inch squares, you could probably just change those lines manually. The grid is a grouped entity, but you can unlock groups by hitting the Locked button in the bottom right, and now you can just use :CC2MCHANGE: on the grid lines you need to make thicker.

Note that you normally make maps in CC3+ in real-world scale, not paper scale, so grids aren't normally specified in inches, but since this is a rather abstract map, then perhaps you should just treat one map unit as one inch in this case.

The instructions can be put in the map description map note. Just provide it to me in a plain text file.

As for the image, yes, I can add that, but you need to change the path. The atlas should work without people tracking down files and copying it to the correct place, you have to change it to use $..\Resources\Bitmaps\WeathermanSweeden\imagename.png

It's more about the tone of the settings than the colors of the map. Just think "the world is not a happy place" and adjust whatever you need to accomplish that. Ruins, war and conflict are all central elements.