Hello and thank you in advance for your consideration.

I plan to build a panel and frame wall in our living room. After searching the forum and the archives for several hours, I could still use some counsel. 

The living room is in our six flat in Chicago. The ceiling and walls are re-framed with new 2x4s to obtain flat surfaces. Electrical has not yet been run so we can position outlets, switches, TV, speakers, and sconces as we wish. The room is 24’x20′ with three windows and a door to trim; ceilings are 9′. The window wall is external, one wall will contain a decorative fireplace, one wall covers the brick wall that separates the neighboring condo, and the final wall separates the living room from the master bedroom. All walls, ceiling, and trim will be painted.

I’ll write what I propose and request your corrections and suggestions.
1. Upper wall: Drywall top 3′ with 1/2″ on all walls except master bedroom; use 5/8″ on master bedroom wall, with some insulation for minor sound deadening in this wall. 
Q: I’d like to consider double layer of 1/2″ and green glue on this wall.Is this method used on walls?

2. Lower wall: Install on lower 6′ high 1/2″ birch plywood with vertical grain, then  frames of 4″ wide 1x poplar, perhaps assembled with pocket screws or biscuits. For now we plan not to use internal frame trim like cove. Cap the top of the plywood with a chair rail (at 6′ off the ground) and some trim, perhaps cove, below the chair rail. Chair rail could be screwed and plugged, perhaps toenailed to studs. Baseboard and cap at the floor, which is quartersawn red oak natural color. All chair rail and base cap mitre returns at window and door casing.
Q: Bedroom wall will have insulation for a little help, but what to use for sound deadening on lower? Shall I install 1/2″ drywall behind the 1/2″ birch plywood, connecting with green glue? Instead of 1/2″ birch plywood, should I use 3/4″ plywood in addition to 1/2″ or 5/8″ drywall?
Q: Better chair rail attachment and trim?

3. Recepticals and sconces positioned not on but within frames, symmetrically if possible (centered between stiles). While I prefer the appearance of horizontal baseboard receipticals, I need to check local code.