Help with room setup on a new build (1 Viewer)

[funk0311]

Okay, I am fairly inexperienced with home audio. Building a new house and trying to get a decent sounding system in the bonus room. I want atmos and the best possible sound I can get for the room layout.

The TV will be on the wall that is shared with the Garage Hall. On the opposite side of the room will be a pool table, so its not solely a home theatre.
My AV guy sent me this on the proposal,

and sent this in a reply to an email I sent.

Based on what I recall from our appointment (correct me if I'm wrong), you plan on having a pool table & a very large TV w/ some couches in between. With the large sliders / windows & what I am guessing is a tile/wood flooring, I would recommend leaving the wiring has we have laid out. Being able to control the acoustics in this room vs. a wall to wall carpeted theatre is going to be nearly impossible. With (4) ceiling speakers, the in wall subwoofer & a multitude of ways to approach the front L-C-R channel speakers, I believe a I can deliver you a tremendous sounding system.

If I pivot to provide you added on wall wiring in the rear sides and rear corners, sound would have to push through the entire pool table area before it would be hear as rears when seated on the couch. These on wall items would also be more visible.

Im not sure if its just sketchy salesman talk or if this really is the best way to go about this. Are in wall subwoofers any good? Would I also need to reinforce the wall it goes in to prevent rattling? What would you do with the space?

Thanks in advance everyone, I really appreciate the help