Can you use gold in the auction house?

How does the currency system work in this game with the zen and astral diamonds?

you can't use gold for auction house
you only use diamonds

how do you get diamonds / zen?

zen is with real money or trading diamonds for it
diamonds you get for selling stuff on auction praying and doing the dailys i think that's about it

are you supposed to get diamonds from praying every hour? I only got diamonds the first time, every time after it was just a consumable.

you get them every time
you have to refine them

You don't, only first 1-2 times per day.