Did you use the "turbulent" check box when generating the forest? I find it makes for a nicer bump map. Also, when applying the bump map, try the other options (linear, spherical, sinusoidal) as they have very different results.
As for the colour, I just tend to keep playing with the HSV, as well as had painting on the colours layer with different shades until I get something I like.
Is there something specific about the rivers (generating the emboss?) that is giving you problems?
And you're welcome!