In examples i found how to tune only cast_shadows, color and volumetric light properties. But how to tune power and rolloff light properties? And may be there are other light properties?

power=object size
roloff is in cone light (check cone obj)

The problem with falloff was solved. Thanks. But I'm interesting how to set in World Editor point light with small range. And last question. Is there possibility to set decal texture to light?

I don't see anything about how to increase or decrease the actual brightness of the light and not the just range?

Just change the emitting colour to something darker?