Upholstery and egg crate type foams will not be rigid, and may not be flame retardant. EPS and XPS construction insulation foam are lighter weight, more rigid, and could be covered with batting and fabric. They come in 4'x8' sheets, but can be cut with a utility knife into smaller sizes. They are available from a big box home improvement store like HD or Lowes. Not sure if they are flame retardant. Depending on how large a piece you are mounting, I would think they may be light enough in weight that they could be mounted to the wall with 3M removeable hangers of some sort.

Leather sofas can really dominate the room and can give an overall cold feeling. I would add some earthy elements, like a wood coffee table with glass or metal. Go to Restoration Hardware's website and look at their sofa room scenes. And I'm sorry I think the art is too harsh for the room. That's all your eye goes to in the room. too overpowering. I would look for something softer or maybe a cool mirror and I would add color to the room with pillows and some colorful lamps. I also think woven blinds would look great. They add warmth and give a finished look. The color of your window treatments should contrast your wall color a bit, not match it or else it starts to look generic and blah.. You have warm walls, warm floors and the woven blinds, like Hunter Douglas brand would pull it all together for you.

So sorry.....I see the dimensions on your floor plan now....oops. It was middle of night here. You have a great place with lots of options. I will try to find a picture for you, but here is what I would try. TV on left wall. Put it on a console table 20" to 30" high, or wall mounted with a wall mounted console below. TV should not be too high or too low for viewing pleasure. The main walkway to the balcony will be on left side in front of TV. To see how the arrangement feels, Try your sofa on the right wall facing the TV. Then put one of the chairs in front of the sofa with its back to the glass and the other opposite of it with the back to your entry. If you feel this arrangement is too far from the TV, a sofa table can be used behind the sofa to move the whole seating arrangement forward. Then if this feels good, you can add a rug. The rug should be at least big enough that the front feet of the furniture can rest on it. You will then need tables on the sides of your sofa. You have the choice of a coffee table or what is called "cocktail ottoman" which you can put a tray for drinks and food on, but still put your feet up. That is always nice when watching TV. If you like this arrangement and go to buy new furniture pieces,get the chairs on each side of the sofa that swivel so the person can watch TV easily. You need to think a lot about what colors you will use in this houses if any rooms are done, take some cues there. It's a big decision that will influence every purchase. Find a 3 color combo that appeals to you. Again look on Houzz at the living room pictures. Post some here that you like.

I think all white will be a very nice scheme and the differences in the white will just add subtle difference. In the above pic the walls are more white than the table, but mixing with the light tan colours and greyish tones makes this gradient of whitish tones work well.This room is all white as well with the furniture and walls, but adding the punch of the other colours masks if the whites are slightly different as the bright colours become the focus. The walls in the pic below 'read' a very pale grey so that would be an option, just ensure that it is a whitish-grey and not muddy or warm. I would choose the sofa colour as your main colour and accents to match from there.