Lots to think about here.

Make sure you REALLY want the tv up there. Putting a TV over the fireplace can make the TV too high for comfortable viewing.

Various companies make wall mounts for tv's. Sanus brackets are very popular. Consider a tilt mount if you put it over the FP. You can then angle the screen down towards the viewing area.

You may not need to cover the brick. Have an electrician cut a hole in the brick and mount the electrical box behind the TV.

Put all your components in a cabinet near the FP and run the wires thru the wall and into the TV.

I may have made this sound simple. It isn't. But a good installation company can do it.

Here is a link that might be useful: {{gwi:1514593}}