Yeah my earlier suggestions of cutting holes in the side wall to place speakers was just an out their idea to get you thinking of alternative options. would be simpler just to go with the top wall. What is that 11'10" wall lined with that requires extra framing to support a TV? One idea is to use an articulated screen mount like I have:
http://www.aavara.com/en/products/product.php?id=71
This allows the tv to be positioned out into the room from 4" to 22" out which allows it to float out from the wall and be more in line with where your speakers will be placed in the room. Also allows you to tilt the screen a few degrees down so the seated person is looking straight at the screen (very important for passive 3D TV's)
Equipment Rack could be located anywhere you want or if you want a tidy look put it in the mechanical room and run IR transmitter to there.
And one final crazy idea to think about just for fun:
Build a baffle wall a couple of feet out from the top wall with holes for your speakers. You can access this area from the mechanical room through the side and mount your equipment rack in here hidden behind glass cupboard doors. Wall mounted TV or acoustically transparent projection screen.