Selecting surfaces based on orientation.

Hi all,

I have here a model I've created in the likeness of a pine cone (or some of my friends say a turtle shell).  The pine cone's scales are made of different surfaces forming a pyramid shape with the apex at the center of each cell(scale of pine cone).  
I have used the plug-in Heliotrope to position the sun.  I would like to do a few things:

1) I would like to select certain surfaces of each pyramid as they become to face the sun.  For each scale I would like to be able to use the angle of the sun in comparison to the normal of the surfaces to select the surface that is most directly facing the sun. This is complicated because the tree structure of the surfaces now splits each surface into a branch with its own scale but then the triangle that make up each branched pyramid is random (i.e. 0 isn't just the most north facing surface with the rest listed in a clockwise manner)

2) I would like to deselect or make inactive the scales that are shaded by the form itself.  Right now the vectors pointing from the surface toward the sun sometimes go through the overall form when in fact they wouldn't see the sun at all.

I know that these are sort of strange questions but your input would be much appreciated!