I start with three main surface layers; hills, sands, and grasses. The hills layer normally would get fake stones shaders with lateral displacements, the largest scale set to 1/4 of the hills height. I use slope for control of 'where' the hills start.
Next, I move onto the sands shader. I use the shaders base color, something between the extreme dark color and the extreme light color. This also uses a slope control, which I adjust to whatever slope angle I think looks right. The extreme dark child surface layer gets about 0.7 coverage. Then I do the same with the light sand child surface layer. Both layers get very small displacements along the normal. These give nice color variation of the total surface. Since the Parent surface layer is farther down the hierarchy, some of the hill shader is covered as well.
Now select the main sand surface layer. Add the smallest and largest coverage fake stone shader from the child menu. Little rocks get covered by larger rocks. I use surface layers for the surface shader input. This seems to stop the exploding rock difficulty.
Set the scale to something you can just see on the preview. Coverage of 0.5 is a good starting point.
You can create new fake stone shaders the same way. You can assign the same surface layer from the first fake stone shader. Just incrementally increase the scales. The coverage should be reduced, maybe by 1/3 for each fake stone shader added.
I hope this clears up what I am trying to say. As an American, English is not my best language. It is the the one I speak (and write), but I am not very good with it. I suffer from the idea that everyone knows as much as I do, so I skip parts of explanations. If you have more questions, I'll be glad to give whatever help I can.
A note on power fractals. Don't use them for the color function or displacement noise of the fake stones shader. The power fractal displaces by a range. This is both positive and negative. It's what is used for terrain creation, so the pos/neg is necessary. They can later be used from the surface layer the fake stones shader points to from its input. I would only use them for coloring from within the surface layer. In the surface layer displacement used for the fake stones shader, I use the perlin noise function. The perlins noise scale I use is about 1/5 of the fake stones scale. Any number can be used for the seed.