Finishes: Colors & Stains

Those are: casino model, door security and vault door. So my question is, I've to buy them er'time I do the heist or is one time buy and I'll have it in every set up I do?

You can mark certain locations on your map by pressing Y to place them, or press Y again to get rid of them. it doesn't act as a waypoint because they don't appear on the radar and you can still mark these points with the waypoint. It can save the location of places you want to visit, but later in the game.