Quote - ....

The second is sort of vague, due to my limited understanding of such things: how does the light falloff for inverse square attenuation relate to your preferred Poser units and/or to the scale of your scene?  Inverse square falloff should be mathematically correct for realistic lighting, but doesn't it also tie your scene to a fixed scale, using whatever units are utilized for the distance calculations in the falloff?...

In one way it relates to the scale: When you have light attenuation (linear or square), the light intensity changes with distance from the lightsource. But the light source has an intensity and a color, so the question arises, at what distance does the light have the intensity and the color you assigned to it? With Poser this happens to be the case at a distance of 1 Poser native unit (regardless of what you use for display units, so if you use feet it will display as 8.6 feet and so on).