This is really good work so far and is going to be a wonderful preset!
About the water in your image. I like it better without.
I certainly would like to test it and in my opinion a couple of little things could be improved. The texturing for example which slightly lacks variation somehow, although you've used a couple of colors.
Maybe some more slope restricted way of texturing gives a better impression of actual real different types of soil/layares/rockstructure. As is now it looks a bit the some throughout the whole terrain.
The trick for coloring stones works very good.
All in all this will be a wonderful learning tool for everyone
Generally, when I write instructions for my presets I try to assume that the users vary from inexperienced to very experienced.
I try to go through every relevant node and deal with the why and how of the settings. This is for the more inexperienced users.
After that I try to drop a few suggestions on what is possible as well and that's for the more advanced users.
If you like I can try to help
Cheers,
Martin