If i have multiple ancient waystones, i can use each ones action once per turn right?

example. i have 3 waystones, I play a spell tactic, i spend 3 resources to activate all 3, and deal 3 damage to the corresponding units.

other question is, Per turn, does that mean per my turn, or each turn of the game.

Yes, you can use all 3 when anyone plays a spell, but each one can only be activated once per turn. And yes, its each players turn, not just each one of your turns.

I dont have the card in front of me, but the elf building that came out in the latest Battle pack "when you play a spell, gain a resource" I'm assuming if i play one spell, and have three of this building out, im going to gain 3 resources? Or do i need to play 3 spells? can anyone explain the specifics of how the action mechanic work in this sense?

When you have 3 of those buildings, you get 3 resources when you play a spell. Every card's effect is triggered, because they all have the same effect. You shouldn't think of them as "the same card" but 3 different cards.