Exactly what above said. I would move the couch a little closer to the tv and then add a console table behind the table. Not a dining table..console table.

I'd also get a coffee table too...not too big. Don't want to block the walkway. Maybe an ottoman that you can also put a tray on (double duty as footrest and place to eat/set drinks).

Also no end table. Would block your walkways..there's not enough space in here. Use the coffee table/ottoman and console table for the things you would use an end table for.

Would putting couch on the half-wall block the walkway from living room (this room) to the doors in the background? Talking about the doors to the side of the tv/under the staircase.

It's awkward because it's too empty. Put a console under the window behind the sofa. Add a lamp. Put a couple upholstered cubes under it for handy extra pull up seating. It needn't butt to the sofa, put it against the window wall. Add a coffee table, and add a chair. Remove the curtains, and get some that TOUCH THE FLOOR in a nice neutral color. Add a woven shade underneath for privacy, so you need not pull the panels closed. Get some pillows for the sofa.

I think you've got plenty of room for a dining area. Definitely move the sofa closer to the tv, as close as feels comfortable.

I have a similarly long narrow living room, and I have my dining table behind the sofa. It has two drop leafs, and I leave one down against the back of the sofa, unless I need to seat four, giving more walking around room. I agree probably no side tables, since you need both sides to be open. But you could get away something like this which could slide over the sofa arm when not in use:

https://www.overstock.com/Home-Garden/Eliza-Snack-Computer-Table/10191197/product.html?recset=5e3486a3-ff19-468d-bd4a-1005872aadbc&refccid=US7Q5VY22APIR62FBFGRUXRVJI&recalg=872,873,839&recidx=0

Console tables are nice in big houses, but what are they for? "Decor"? You don't have enough house to be wasting sq ft on furniture that's going to be only used for holding up a couple of vases. Might as well have something useful, even if it's only used when monsoon winds are blowing the rain sideways! If you're sure you don't want a second indoor dining space, think about something else useful you would like. Records and turn table? Bookshelves? Bar cart? Storage bench under the window (beach towels maybe)?

Desk?

Try a sofa table, like in this project of ours below. Notice the table behind the couch?

Alpine Ski Home · More Info

http://www.crutchfield.com/S-4zsynTUU56q/learn/learningcenter/home/TV_placement.html

Here's a handy chart to help you get it right.