The displacement is based on a normal map. A normal map is basically a grid of vectors encoded using RGB values so you can store it as an image. The vector encoded in each pixel basically determines the direction for the displacement effect at that point.

The texture size tells CC3+ how to scale the texture you pick. If you want a single displacement image to cover the entirety of your map, set the effects units to map units, and the texture size to a value equal to the width (or height) of your map. If the value is lower than your map size, the displacement image will tile (which is usually the way you would use it).

The displacement amount is basically the strength of the effect, i.e how much the pixels should be displaced. May need som experimenting to get this right, and don't be afraid of going to pretty large values.

It is a template file, so it won't show in the CC3+ open dialog unless you change the file type filter to show templates instead of maps. You would normally using the new map wizard (choose a pre-defined template) to create a map from it though, not opening it directly

The file Ralf referred to above is still located in the same location for CC3+, just look in the CC3+ data directory and follow the path. This is a Cosmographer supplied filed though, so you need to have Cos3 installed, there isn't one available for "plain" CC3+.

Note that the next update (the one currently in public beta) have an improved version of the text along a curve command that handles this issue.

In :CC2PRESETS:, make sure to pick the correct draw tools (These are the names of the folder the tools reside in). Obviously, you should do this in the template to ensure new maps crated from it will work properly