Congratulations! I just moved into my house and I am in the same boat as you as far as decorating goes. The dark wood is amazing, I definitely would not recommend an area rug because it just takes from the modern look.
As of now, you need a TV stand. Might I recommend a floating stand such as this Atlus Stand to keep the floor as the center of attention. After that, invest in a few accent pillows to add color to it. With brown you can go with anything from orange, to yellow, to maroon.
Also a pretty cool investment if you want to make your house smarter would be to invest in a Phillips Hue system to control the lighting in that room, in case you need to set the mood.
General thoughts:
It looks way better not in that stand.
Most people (me included) will tell you it would probably be more comfortable and better ~12" lower. Eyeheight should be roughly middle of the screen.
I haven't seen a soundbar that lets you do seperate L & R channels, with itself basically acting as a center.
Nothing at all weird with having speakers left & right of the screen. You've got a pretty good setup for that, actually. R would be flush with the hallway, left near the door.
Find something that fits your needs, but I'd combine something like this with a wire cover painted to match your wall.
Have you considered a custom mantel? I'm not sure how much money you have available, but my family just had our house built and I had a custom mantel built just so I could house my consoles and router below the TV for easy access. This is especially nice to not have to worry with the kids messing with everything. Here is a picture of what it looks like.