to a male: tadlik et ha or (תדליק את האור)to a female: tadliki et ha or (תדליקי את האור)
in the light = ba'or (באור)
"Or" (אור).
or ha'olam (אור העולם)
Or yafeh (אור יפה)
well most people say turn off the light but you could say switch of the light.
to a man: atah ha-or. to a woman: at ha-or.
You say "turn on the light" because that is what you do. Turning on a light means to flip the electric switch from "off" (where there is no electricity and the light is dark) to "on" (where there is electricity and the light is glowing).
kiba (כיבה) means to extinguish (fire) or turn off (a light).
You say 'Yalda' in Hebrew
Probably not.
light of the world = or ha'olam (אור העולם)
It depends on context. For example: to turn (yourself) = lashúv (לשוב) to turn (something else) = lehashív (להשיב) turn (in a game, ex: "It's your turn") = toor (תור)