Try adding a new Glow to the WATER sheet, move it up to just below the Color Key and set it up like this.

You might have to adjust the extent of the water to take the edges outside the ribbon border so you don't get pale colours seeping in from the edge all around, but it should work. The drawback is that all the rivers will be that lighter blue.

I also really recommend moving that title back to the top corner where it was. There's a natural space for it there.

On the Bevel, Lighted it is possible to make the bevel concave by increasing the value of the Slope Curve.

With a bit of fiddling you can reverse the shading to show the effect of a hollow by unchecking the Global Sun Direction and setting the Azimuth to 180 degrees from the global sun settings.

With the ordinary Bevel, you can't make the curve concave, but you can reverse the shading by checking the Invert Colors box. That would make the polygon appear to be sunken instead of raised.

If you use Draw -> Insert file, you can import the bitmaps and decide at that point how big they will be by the placement of the corners with the cursor.

CC then asks you for the first corner, and then the second corner. If you have a snap grid turned on you can put them down at any exact size you want.

I don't know if there are any settings you can alter for the result of drag and drop.

Yes. But every last one of those several contours would have to go on it's own sheet.

At a rough count that would be 12 more sheets than current.

The easiest way is probably to pick a single tree symbol and scale it to the size you want all the trees to be (without actually pasting it). Then right click with the tree still on your crosshairs and note the scale you are at. Here, below the scale is 0.2.

Then click Finished and go to the Drawing Properties button and set the scale in the Drawing Presets that it opens to be the same as the scale of the single tree.

Then, delete the forest you've just drawn and redraw it. The new default symbol scale will cause the trees used by the tool to be rescaled to the size you want them to be.

In this test map below I set the default symbol scale to be 0.5 instead of 1, then drew a new patch of forest on the left. The existing patches of forest on the right remain at the original default scale that was set when they were pasted (1). That is why you need to delete and redraw the existing forests that are the wrong scale.