Radiosity Questions

Hi, I have just started reading about Radiosity but have found the few paper i have read have left me incomplete to say the least.I have a few questions that hopefully some one can clear up for me. 1) Many examples use a HemiCube for determining the Form Factor between two faces.But i dont have to use this do i? Not if i have the Form Factor formula and a Line of Sight function, i can use this unstead cant i? 2) Every example that i have read subdidvides the polygons into patches for higher resolution and calculates a final color for this patch.Now the thing is is that i want to use radiosity to generate light maps but am a little unsure how this relates. Say for example i want to generatre a 16x16 Lightmap, would i divide the polygon (temporary) in to 16x16 patches and the final color for the a patch would be the color of the Lumel in the Light Map? Ehat i mean is each Lumel would correspond to a Polygon Patch in the same grid position. Thanks in advance