Speaking of the randomness, could you be more specific on how it works?
For me the randomness on scale, rotation and color was determined by the system I described with this image : http://wiki.inkscape.org/wiki/index.php/Image:Random_spray.png
Which means that if your randomness is 100%, then the parameter takes any value between the Min and Max values.
If randomness is 0%, the value of parameter is the mean between the Min and Max values
If it's 50%, then the parameters is more likely to take the mean value than the Min or Max itself.

Steren