The current taken is less as well due to flowing upwards with a constant voltage. So cheaper to run.
Not really, the electrons flowing out if the device (downwards) will be drawn out faster due to gravity. Also, as there is a similar capillary action to water so pulling the flow of electrons through the device. Therefore the net 'advantage' of gravity is zero. Q.E.D.
Stress - the condition brought about by having to resist the temptation to beat the living daylights out of someone who richly deserves it.