Disagree, they are reversing lights, you are not necessarily parking when in reverse. Parking lights are put on when you are parked. Anyway whatever you call them, they arent enough in the wet.
Totally! Once visibility is reduced the dipped headlights need to be used. its not about you seeing objects - its about others (pedestrians, cyclists and motorists) seeing you.
In the absence of street lights etc, it may be appropriate to leave your parking lights illuminated for safety reasons.
This will not usually drain your battery. On certain high-spec, high-tech cars ( ), if the indicator stalk fails to self-cancel with the car parked, the front and rear parking lights on that side of the car will remain illuminated (but not the indicator), even with the light-switch in the "Off" position. An irritating buzz / beep will alert you to this when you remove the key from the ignition.