I don't get the problem. Apart from the mix/max step lens attribute on the partiVolume, volume container size and grain are unrelated as far as I know plus I don't see any noise in the render. I don't use the "physical light", a regular Maya light with a quadratic falloff is more accurate so I don't know if that is part of the problem, it could be dying before it gets a chance to illuminate the scene. I can't imagine why the camera being inside the volume makes the lights not render :s.

This is a render that is using a renderable camera and it's inside the volume primitive.