Regarding inflating props: You turn off smoothing for individual props in its properties

I have no problems running the script multiple times - I do it every time I change lights. So I cannot help there
It also does not turn off or negate the AO I set on other props, figures or lights.

The bad texture warning is usually a sign of lack of memory. Depending on how much you have in the scene it might have to do with the render settings. Be sure to use the external renderer, this will easy your memory requirements when rendering. Also do not use the Automatic Render settings - use the advance ones and do not set the raytrace bounce, pixel samples and irradiance caching too high if your scene is complex.
Other possible cause for running out of memory in Poser is if you have theTexture resolution in the Preview mode set too high - lower it to 512 if you have problems