I forgot to reply to the attenuation question:

Generally attenuation in 3d graphics is how something decreases when objects are farer away. For a light it is how brightness decreases over distance. So it probably will fade occlusion off over distance. Maybe the translation of attenuate helps a bit:
http://dict.leo.org/ende?lp=ende&lan...earch=attenuate


Models, Textures and Games from Dexsoft