i have some questions on this topic that hopefully someone can shed some light on (pun intended)

if you switch the light on and the bulb is busted does it still consume power? if it does, does it consume as much as if when the bulb is still working? if you switch the light on and there is no bulb attached to it?

if an appliance is plugged in does it still consume power even if it is turned off and it does not have a standby mode? (electric fan as opposed to tv)

does turning on an a/c consume a lot of power so that it is more energy efficient to leave it on overnight than to have it switch on and off (on 2 hours / off 30 mins, repeat)?

TIA for any advice on the subject.