I'm sure the dust can be done via the surface shaders as particles might be overkill for what I assume is going to be a static image. I can't see why textures in the dust layer wouldn't work as long as there is the appropriate mask being applied.

Check out this shader, I can't disect the shader network since I don't have renderman.
https://community.renderman.pixar.co...typot.html?l=r

From my passing knowledge of seances, incense, personal objects beloning to deceased people etc seem to part of the deal sometimes. As far as the lighting goes, the distribution seems a bit off. Are you using a linear lighting workflow?