in here i'll post questions that will help me tie up some loose ends after finishing the main story and hope some kind community members can help me? if anybody else wishes to post any questions feel free.

first up i need some (2) dark essence, any idea where the monsters i need to kill spawn so i can get some?

You are in luck, dark essense is fairly easy to come by and there are several sites around the southwest of velen where those kind of wraiths respawn.

I'm trying to find more light essence, but those wraiths NEVER respawn and shopkeepers never have it.
Only random loot can provide it and I've only ever found one in them in said loot, so far. ;..;