im guessing its preferable when u need a polygon that will be seen on both sides in lit conditions that its best to draw it twice once using GL_CCW + once with GL_CW instead of drawing just one polygon once + disabling culling and enabling two sided lighting. i take it this holds true even drawing multiple polygons. of course this is all dependant on the card
This is sometimes true and sometimes false. Depends completely on the implementation.
Note that it is illegal for the driver to do this internally: it involves reordering primitives, which is not permissible in OpenGL, because it can change the rendering results.
ive decided to go with the 2 polygon method which is a bit of a pain (esp since im also doing the modelling but it does seem the more straightforward of the two ways ie less likely for cockups to occur