Okay hello i have little question.
Is caves/ruins respawning enemys like draugs, skeletons, vampires......?

Anything you found in a cave/ruin the first time you entered it will appear in it again.

How long is respawning time in-game? Have u any idea? Im lvl 67 and im not yet cleared caves/ruins other time only once.

If i remember it is a week or a month not really sure cause once I've been in a dungeon once I never go back in.