Your room will work, although your ceiling is low. Everything is affected by dimensions, but there are ways around all of that. I would suggest you visit our web site at www.advancedaudiovideo.com
which will have much information that you will find useful.
A big concern is to keep chairs away from walls, if at all possible. As far as doing the "extra" walls, this is only needed if you're wanting to do sound isolation. Truth is, we do many large homes (our largest is 400,000 sq. ft.) with theaters that never do any isolation. usually your guests are in the room with you. The majority of the sound you will hear outside the room are the lows (booms, etc). These are usually just a dull rumble, even if you have a very powerful system. Most of the highs are never heard more than about 20 feet away.
A major problem that most people have in a room this size is putting speakers to high. If your seating is next to a wall or against the back wall, and the speakers are above your head, this is very poor audio design. The picture is easy enough to do and get right, but if you don't design your audio, it could mean great dissatisfaction in the use of your room.
When designing your audio, use mirrors. Place a mirror where your speaker will be, then shine a light on it from different directions. Where the light shines is how it will hit the listeners ears. You don't want to have a chair next to a wall with the speaker coming out directly in your ear. You need to be a couple of feet away, at least.
Anyway, there is to much detail to try to tell in a single letter how to design your room. It will work, but do your research. Think about wiring for WII and Nintendo as well. These are great rooms for these games as well.
Again, go visiti our web site for more information.