Bricks, Masonry, Asphalt and Concrete - Replacing exterior brick from kitchen vent hole

My kitchen has an exterior vent box from an old Nutone fan. The fan box (not the fan) was left in place when the kitchen was reno'd; this was done before we purchased the home. I'd like to remove the box from the exterior of the home.

Question: how hard is it to remove the fan box and replace the brick?

I have a style of brick that is red with small vertical lines running though it. How can I tell if my brick wall is a supporting wall? I assume it's not since they put a hole through it :) WHere can I go to find a matching brick? Can I just call a brickyard and ask?

I wish I could use the old vent, but it's placed too low as it was meant for a Nutone circular vent. If it were 1' higher I could run a range hood out to it...