Yes, delete it, it is just leftover construction aids.

The Dundjinni Archives also have some Sci-Fi stuff in them

The orange line is the roof ridge for that style (It looks better when you zoom in much further). The reason it sometimes seem to disappear when you zoom out is that it simply becomes to narrow. Your screen only have a finite amount of pixels, and when something gets thinner than a single pixel, a decision will be made if that pixel should be displayed or not. Being less than a pixel, if you use a pixel to display it, you take away space from something else, so showing everything is simply not a technical possibility.

The same is the case for exports. A sufficient high res export may have more than one pixel available for each ridge, eliminating the problem, but generally, every export will have it's limits, just how images work.

My players would murder me. They're terrible with number puzzles..

Embedding should work fine as long as you give it a nice clean Twitter link to the tweet:

Make sure to only use it on maps/templates though, and not on symbol catalogs, since a symbol catalog by it's very nature is a collection of symbol definitions that aren't being used anywhere.

Looks nice, but that road in the top right part looks a tad to compass rose straight. Would look a bit more natural if both that and the bridge was on a bit of an angle.

The oasis is now found in the community atlas. Thanks for the contribution and welcome to the atlas.

Your roads are a bitmap fill style, which means it should show up on the Bitmap Files tab in the fill style dialog. And you can use Info -> List on the road to find the exact name of the fill from the dialog if required, then from the dialog you can find the file name and path, if needed.

As long as the image file is installed by an official product, and it lives in the CC3+ data directory, it is ok. If it isn't already a symbol, be careful when making it into one though. If it doesn't already have the four different resolutions (_VH, _HI, _LO, _VL), DO NOT tell CC3+ to create them when importing as a symbol, as that would change the image name, resulting in something only you have. Image files must be used exactly as they were installed by the product.