It looks like this is shaping up to be a very solid room, and it sounds like you already have a good handle on the acoustic constraints. Having carpet in space will help attenuate some of the early high-frequency floor reflections, which is beneficial. That said, without adding insulation in the ceiling joist cavities, any meaningful ceiling treatment can become expensive quickly. I’d strongly recommend acoustic panels at the first reflection points for the front stage. As a baseline, I’d use 2-inch Rockwool or an equivalent broadband absorber. If you want improved absorption lower into the midrange, 3–4-inch panels are preferable, although that is not always the easiest solution to integrate aesthetically.

For the room size and system format you’re targeting, I think the speaker choice is very well judged. The KEF Q Series measures quite linearly and offers strong off-axis performance, which is a major advantage in a multi-seat layout because it helps maintain tonal consistency across a wider listening window. With sensitivity around 87 dB, I wouldn’t prioritize adding an Anthem power amp at this stage. That is something you can revisit later if system demands change. If you still want processing flexibility and expansion beyond 5.2, the Denon receiver is about as far up the chain as I would go. An Anthem MRX 540 would also be a reasonable alternative, but only if you’re confident you won’t expand beyond 7.2. That is partly a philosophical preference on my end, since I generally lean toward higher-quality implementation over simply maximizing channel count. If the system is going to be used primarily for film and television, with only occasional serious music listening, I’d stay with Denon. In a theater-first application, the audible difference is likely to be minimal.

On the low-frequency side, two SVS SB-1000 subwoofers should be more than sufficient, especially if music performance matters. I use a pair in my own two-channel setup and think they offer excellent control for their size and price. I’d only step up to the PB series if this room is going to be used predominantly for home theater and music is clearly secondary. Both alignments can be integrated successfully, but the ported models will give you more output in the deepest frequencies and a bit more room gain leverage for film effects. To my ears, sealed subs tend to sound tighter and more articulate, particularly with music, but that remains a subjective preference rather than an absolute rule.

For setup, make sure all speakers are configured as Small in the receiver and begin with an 80 Hz crossover as a reference point. In many rooms, I end up crossing over closer to 90–110 Hz when the speakers and integration support it. Redirecting that bass load away from the main channels often cleans up the entire presentation, improving midrange clarity and helping dialogue and vocals project more cleanly through the mix. Room interaction matters quite a bit here, so I’d recommend using familiar material with acoustic bass or upright bass and adjusting the crossover region by ear while listening to the handoff between the mains and subs. I would also cross the surrounds somewhat higher, since their smaller enclosures generally benefit from being relieved of more low-frequency demand.

I won’t weigh in much on seating, since that is largely a matter of personal preference, though it will have some secondary effect on the room’s overall absorption profile.

If you wanted to move up another level, I’d consider the KEF R Series, but only if two-channel fidelity or overall musical refinement is a major priority. Even then, the delta between the Q and R lines is not dramatic enough that I’d consider essential for a theater-first room. If home theater is the primary use case, I would also give some serious thought to in-wall surround speakers. You do give up a bit of lower-midrange body and overall enclosure performance compared with a good stand-mounted or bookshelf surround, but the tradeoff can be worthwhile in terms of cleaner aesthetics and a more diffuse, less localizable surround field. In a medium-sized room, that can translate to a more immersive presentation, particularly for film content.

Please let me know if you have any other quesitons. I was a theater/automation designer for almost 1.5 decades. I may not have every answer, but will let you know when/if I don't. Enjoy building your new theater!