Great to hear from you again. The openings to the secondary area (kitchen, breakfast, and dining) is a large rectangular arch (8ft H x 5ft W) - and is on the same wall that the TV is mounted, at the left most side.
The other 2 openings - 1 to the stairwell and the 2nd to a landing and bathroom are along the adjacent wall - perpendicular to the main opening noted above.
As far as sub placement, I am aiming to put it in a corner - assuming it ends up being a favourable spot after the woofer crawl test
One of they key reasons in asking this seemingly basic/elementary question is that I am in Canada, so I want to avoid having to process a return etc in case the sound is not what I expected etc.
A while back, I did purchase a Klipsch R-10SW to get a sense of what adding a subwoofer would do for the sound - I placed it along that wall (no time for a subwoofer crawl) with the TV and I was pretty happy with the result - however the sub could not handle higher volumes or very low end bass - so this did teach me that:
1) I need a more powerful sub that can easily pressurize the space
2) A 10 inch sub is NOT sufficient
3) My receiver is sufficient for my needs
4) Having the right "HSU" will make a huge improvement in comparison.