Well here is my findings so far.

If nobody else answers it have to do..:))

1. 3D models. To soften the edges make a copy of the layer with the object and give the uppermost layer some gaussian blur, about 1-2. Then set blend mode to "Darken".

2. When all the models are done. make a copy of all layers by holding down shift,ctrl,alt and press letter E. Then make a new copy of the resulting layer, select this new (uppermost layer) and apply the filter "Underpainting". Set blend mode to Soft Light (or experiment).

3. Smudge painting. Set the Brush Tool opacity to ca 30-40%, sample size of Eye Dropper Tool to 3 by 3 average (this is resolution dependent). Then work throught the whole painting while constaltly sampling the colour by intermingling with the alt key.

To  apply a really good persico skin tone for Poser models use the professional  program Neat Image (removes noice but expensive) For example RGUS uses it.

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To completly change your work into another style, use Erick Nguyen's watercolour method, check link (paste as one line),

http://forums.dpreview.com/forums/readflat.asp?forum=1006&message=12322628&q=ErickN+Watercolor&qf=m

This method can also be adapted for other styles.