Get the rivet to look the way you want it to look, THEN duplicate the layer. Much easier that way ... unless you create all your rivets on one layer first. That's easiest, too.

As for making the rivet just like the background, I would play with the layer blending modes. Make sure the layer style doesn't have a color overlay, though, or the layer blending modes won't work for you with the style overpowering it.