Q:I've been reading about the rules associated with priority (being a casual player, I didn't learn about priority until recently), and I was wondering if something my friend does is allowed. He likes to activate tap abilities at the ends of his opponents' turns so that he can immediately untap his things at the start of his own turns. Does this work? I read that there's a time in the end step where the active player gets priority, but if the AP doesn't play anything does priority go to the NAP?
Yes, exactly as you said. =3
Example would be tapping and sacrificing an Evolving Wilds at the end of an opponent’s turn to fetch up a basic land that is tapped, so that when the turn comes to you, you can untap said fetched land.