Adding floor loads to walls, headers, beams and supporting structure below that were not originally designed to be load bearing can be unwise without professional assistance. It is best to have a structural engineer advise you even when the walls look adequate. Also, it is often necessary to make the new floor structure as shallow as possible in order to provide adequate upper floor headroom and in such a case it is possible to design floor joists that meet the building code but are uncomfortably bouncy.

What do you think about turning the rug 90* (centering it on the fireplace), and then switching the TV and the sofa, so that the sofa is across from the loveseat, and the TV is across from the fireplace? I love the look of twin sofas flanking a fireplace! :-) Also, consider mounting your curtain rods so they are just below the sconces, and extend beyond the sides of the window by 8" or so. I'd buy longer drapes that kiss the floor, as well. :-) I'd let the new rug or a great piece of art decide which direction to take the pillows and paint color. Pick paint last.

IMO you need the chandelier to lower the ceiling visually. I recommend you consider locating an air mover somewhere in the room Usually there is some place they can be placed that is out of sight. Your chandelier looks a bit dated in terms of style. A bit too small for the space IMO. Make sure you get one large enough for your space. If your room is 18x 20 then I'd recommend a 40-48" chandelier Nothing worse than a chandelier that is too small for the space. The light fixture should be mounted lower than where the fan was hung. https://www.amazon.com/Capital-Lighting-428501MB-Homeplace-Greyson/dp/B07CT556QK https://www.amazon.com/Quorum-Lighting-6250-15-86-Brooks-Chandelier/dp/B00IMMUQBG

The ceiling to floor is certainly dramatic. They are probably quite expensive so I would 100% go with Mark's logic. I had a 2 story area like this when I was younger, and I left it bare. It was North facing with lots of trees. Never once did I need to block sun or get privacy - in fact there was nothing on the lower windows. But the 3 other directions would have a much greater likelihood of needing window treatments. You would definitely want 120V up there. Can't imagine changing batteries - if they could even handle those long/heavy curtains.