All else aside you are going to want the windows behind the TV (bottom image) or you will be fighting reflections that will really reduce your viewing enjoyment.

I’d say a single Sub would do well in that room but you can always add a second if it isn’t giving you the sound levels you want. You really need to try several sub locations, for a single Sub I’d go with under the TV as a first try, then try your suggested corner position where you’ll get more sound but it may be less even across the room. If you go with two I’d lean to the side-walls at the TV end of the room. Try them at varying distances from the corner for the best sound. Some folks prefer the Sub flat on the floor under the couch so you might try that too.

I’d not go with a small sound bar, the Arc is going to do a better job of filling that larger space.

The rear speakers, probably should be Era 300s, should be on stands, at ear height and just behind your listening position. Era 100s would work but shouldn’t be your first choice.

Thanks @Stanley_4  ! Really appreciated your insights.