Am I understanding you right here that each sheet is one floor, so that all the floors are in the same map file?

In CC3+, because of things like sheets effects and such, maps tends to use a lot of sheets, so it is generally better to use one map per floor. Although it is possible to keep it as one map too, but then the macros hiding the sheets must be updated to hide the complete set of sheets. With some nice naming you can do this rather easily by taking advantage of the HIDESHTF and SHOWSHTF commands which hides and show sheets by a wildcard filter, so for example all sheets for floor 1 could be named FLOOR1_SOMETHING and so on.

That would be my preferred solution for the poles, yes.

I really loved the map showing all 7000 of the rivers feeding the Mississippi. Kind of cool how it collects water from a really huge part of the US.

Well, that's the problem then. Just move the COASTLINE sheet upwards to right between RIVERS and ROADS, which is where it is supposed to be.

What probably happened here is that the COASTLINE sheet was missing from the template you used, which caused CC3+ to automatically created it when it was needed for that outline. But CC3+ don't know where in the order to put such a automatically created sheet, so it just puts it on top of everything.

Edit: And a fast Lorelei sneaks in......

It's basically two ways to do that. The first way is to do as you mention yourself, chop it into sections and gradually change the line width. The trick is to make the change between segments small enough to not be noticeable (keep the intended zoom level of the map in mind, you'll obviously always see the "steps" when you zoom close enough, for example when you make it, but if the map is made for being zoomed out, ensure it looks great at that scale.). Adding effects to the river like glow or edge fade will also hide the stepping. I usually also place the steppings where the river joins with another river, which also hides the edges.

The second way is to draw the river using a polygon tool instead of a line. This obviously means you end up drawing both banks of the river, but youæll have full control of the appearance. This is a bit more work than using a line, and also more work if you need to move some nodes since you have both sides of the river to work width, but you can make it exactly as you want to.