I agree with the above posters. While I absolutely think this project is do-able, I believe that doing it correctly will require some research and be a lot more involved that one would think.
I'm not a carpenter, though there are several on the forum and probably reading this. I would guess that even if the wall isn't a bearing wall , you will need to pull drywall floor to ceiling and insert a proper header, king studs etc.. The 120 volt and low voltage connections aren't that big of a deal. Bring both up from the bottom. Cut in a jem box for each into the sill facing up from the sill of your tv opening. Leave yourself enough room for the wiring by leaving the sill down 2 or 3 inches from the top of the drywall under the tv. If overheating is a concern, consider designing your header so that air can move through it (either oversizing and drilling holes, or leaving an air gap in the center.) Then you could install a return air grill on the wall at the ceiling to allow passive convection to cool the equipment.
Anyway....... I didn't mean to get so long winded with that, and I don't claim this to be some kind of ultimate design for your situation. That's just off the top of my head ad probably missing a lot. I just wanted to illustrate how complicated I believe the scope really will be if done correctly. Several other options would be A LOT less effort and are already mentioned above.
If you do decide to go ahead with this please post pictures, etc. It will be very interesting to follow.
Marks Brothers Electrical Contractors LLC.