If you wanna get technical, the prefix should be in greek to match the word "-kinesis" - thus, it'd be hydrokinesis instead of aquakinesis. There should also be a technical quirk for the ending of the prefix (ie, pyro instead of pyra), but.. I don't know it. |D
Even more technically, the word "kinesis" indicates movement, but as a neologism in the occult world, it pretty much denotes being able to affect something.
Darkness would be "skia-" or "skoto-" (Umbra is latin for shadow)
Light would be "photo-" (Lumo, again, Latin)
Earth would indeed be "geo" or "cthuo".
Electricity would be "electro" as it comes from the Greek word 'amber' (apparently. o.o)
Temperature's been discussed.
Time would be "Chrono".
Luck could be "tuche" or "tycho".
I assume Reality is the same as Truth (as I've read on Places), in which case it's "Alethe".
This site should help if you type in "greek word for x".