Why can't the doors simply be moved up? If you remove the trim, door and frame, then you could cut back the drywall up top. Next cut out the header,
and replace it with new studs, secured by screws from the inside of the opening. Done carefully, you won't even impact on the drywall.
I would be prepared to black out the av rack, as there is a very good chance you will shortly consider that you made a mistake placing the av rack in the line
of sight. I learned this the hard way, and the next remodel the av rack went in the back of the room. Now it's right outside the entry door.
Glass is highly reflective also, so I wouldn't really want smoked glass up front either...
Whether I pre wired for overhead speakers or not, would be based on ceiling height. If the ceiling is low, then I wouldn't bother. But wire is cheap, as a future proofing