I like your selections and val's suggestions for placement, particularly the sofa along the right wall since I'm guessing you may want to take advantage of the large window. I also suggest floating your furniture a bit so there is a small clearance behind the sofa. Unless the room is very tiny, which yours is not, I think providing that clearance makes the room feel more spacious. I might add an interesting low stool across from the fireplace to provide a minimal visual barrier to the social grouping with the added benefit that it may come in handy occasionally fulfilling its intended purpose of additional seating. I'm sure you'll have fun decorating your new addition and this LR. Enjoy!

I think your room is perfectly suited to such a layout. Even a small bar cart or wine chest on that end of the room would help define the space. It's a look I would have done in my own living room had I been able to bear the thought of giving up my very comfortable sofa where I sit in front of my windows every day!

I like the flooring idea. pick a sofa, chairs, etc, before you pick a rug. measure the space and see if a small sofa w/chaise will work. look at what kind of ottoman you'd like. they have some on wayfair w/a tufted top and weathered sort of wood frame. I actually got one for my living room. You can look at something like that (it has storage under it where you can hide toys and stuff) or just look at the solid ottomans. https://www.wayfair.com/furniture/sb0/ottomans-poufs-c214997.html

1) wall may be structural 2) you may have to replace all the flooring if you remove it, unless you have more on hand 3) I'm confused, because it looks like the dining room is already in the main space, up by the kitchen/window where there's a chandelier hanging down. then I see two ceiling fans worth of LR space. the more enclosed room to the left looks like an additional/separate room, maybe intended as an office, or as a more enclosed space (family room) for TV watching. if you open it up, you need to think hard about where you are going to put the TV with furniture facing it, and how you will subdivide the rest of the space. If you can draw a sketch of the floorplan, with measurements, including things like whether there's a closet near the front door, we might be able to rough in some different arrangements to help you visualize what you might be able to do with the spaces. It's a bit too hard in the abstract to tell whether this is all one big seating space, or whether it's big enough for an entry zone or game table and a separate conversation area, and what would happen if you added in yet more LR space...