I do hope that you carefully think about the painting of the fireplace before you do it. Painting of brick is very permenent. Since it is a porous material, it soaks up the paint. Once you start you can never go back.
We have a brick fireplace that incorporates real stone on the floor next to the fireplace. It has brick around the fireplace but then it has faux rock slabs on the rest of the wall. We are going to paint the faux rock slabs but leave the rest as is. Have you thought about anything you like the way it is and just change what you do not like?