Okey doke. Well I'm glad we're here to help you then!
Thanks for clearing up the question about your room's dimensions. Makes a big difference!
Is the room's width actually 15 feet, 7 inches then? Not 18 feet?
That's a bit of a concern, actually. Not for the speakers and projector, but for your seating plan. Typical recliners are 22 or 23 inches wide for the seat alone. So four seats - no arms yet - are already 88-92 inches across. Then you add in 8 inches for the two flat arms on the ends, and 10-12 inches for the wedge arms to make it a curved row of four seats with a love seat in the middle. So you're in the range of 124-132 inches across. That's 11 feet across. And could be more if the arms are wider. My favourite home theatre recliners, for example, are the Palliser Indianapolis. For the exact layout you showed - four seats, curved, love seat in the middle - the width at the back of that row is 133 inches.
If the room is 15' 7" wide, that's only going to leave you 2' 3" on either side of the seats for a walkway. 2' 6" is pretty much a minimum. 3' is nicer for a walkway. Plus you'll have the acoustic treatments sticking out another couple inches from the wall. It could be uncomfortably snug.
Making the row straight instead of curved could help a little. And you can always go for narrower seats and/or narrower arms. Or you could forego some of the arms and have more of a couch.
But my point is, you'll need to pay close attention to which seats you choose to buy! So long as you're aware going in though, you should be fine
You don't need to have your seats on a riser to get good bass. More bad info someone else gave you. Sorry about that. It must be confusing!
Decoupling the subwoofer from the floor does help though! Much easier to spend $50 to decouple your subwoofer with a SubDude than to build a whole platform for all of your seats, no?
At this point, I'd recommend sticking with the one row of seats with 6 feet behind them. What you could do is still have an elevated floor behind the seats. That way, if you ever have more than 4 viewers, you can easily bring in some chairs and have them behind your row of recliners. They would be temporary only, but they'd get the job done. And that would allow you to have the one row or permanent seats directly on the floor and in the ideal acoustic location, rather than trying to squeeze two rows of permanent seats, and having to sacrifice other aspects just for seats that you said you probably won't need or use very often!
In regards to the screen, aspect ratios and viewing distance.
HDTV is all in 16:9 aspect. But most movies are wider. 2.35:1 is the norm. So when you watch most Blu-ray movies on an HDTV, you have black bars on the top and bottom.
SOME movies are in 16:9 (1.77:1) or 1.85:1 aspect. And really old movies and, of course, standard def TV are in 4:3 (1.33:1).
So the simple fact is that no individual screen is going to perfectly fit everything. You are going to have black bars, either on the top and bottom, or on each side, for SOME content.
I know a lot of people still hate "black bars". But you shouldn't

The director chose a certain aspect ratio. He or she wanted to tell a story and give it a certain feel. So they chose an aspect ratio, maybe more square, maybe wider than normal. But the point is that, if you want to see the image as intended by the director, you're probably going to have some amount of "black bars" somewhere on the screen. You are not "missing" part if the picture! This is simply the only way to see ALL of the picture as intended! If you zoomed in the image to fill the full physical borders of your screen, THEN you would be cutting off part of the image! Lots of people still do this, and it drives me nuts
The good news is, with a projector like the JVC, the black is SO black that you truly do not notice the "bars". They just become a part of the screen's frame to your eyes
Field of view is a different matter though. SMPTE - the Society of Motion Picture and Television Engineers - recommends a 30 degree field of view for HDTV content. From 12 feet away, that is a 88.5 inch diagonal 16:9 HDTV. At a 32 degree field of view, if you had "perfect" 20/20 vision, you would be able to make out each individual line of resolution.
For movies, THX recommends a larger 36 degree field of view. 20th Century Fox recommended as much as a 40 degree field of view, which I've used in my recommendations here.
Beyond that size, you would have to physically turn your head in order to see the sides of the screen. Even at a 40 degree field of view, you will likely have to turn your head, and not just your eyes. So it's not just about being nearsighted. You start to run in to real watchability issues when you go larger. It isn't comfortable or enjoyable to have to physically keep moving your whole head to watch a movie!
So in your room size, a 12 foot viewing distance is about perfect, and a 120" screen is as big as you should go. At 12 feet, SMPTE would recommend 88.5", THX would say 107", and Fox would say 120"
As for what you saw in stores, there could be a ton of reasons. If there is ANY light in the room besides the projector itself, that will wash out the image. Obviously, the brighter the ambient light, the duller and dimmer the projected image looks.
I'm strongly guessing though that you've maybe never seen a properly calibrated image. There is actually a "right and wrong" when it comes to video. There are very precise and well defined, measurable points for each color, black and white, and gamma (the rate of rise from black to grey to white).
Unfortunately, most people have never seen a properly calibrated image! And when they do, they think it looks dull, dim and muted. And that's because TVs shown in stores have long used "torch mode" to draw your eye. They are WAY too bright, the colours are way overblown and over saturated. Contrast and gamma are over done. But all of these things draw your eye. And when there's a whole wall of TVs in a big box store, the manufacturers want to get your attention how ever they can!
But a properly calibrated image looks realistic and has all the detail that the director intended. Real life doesn't have cartoon colors screaming at you. Neither should you movie screen
This could be tough. There's a lot to cover, for sure! But none of this has really changed my recommendations. They all still apply. Whether you'd actually be really happy with all of them though might be questionable now, though
Best thing for now though: read through everything here. Do some research on your own based on what's been said here. Take many deep breaths. And DO NOT RUSH. You've got plenty to learn and consider, and we've dropped a TON of information on you! But it's all in the hopes of getting you the absolute best system for your hard earned money. And it's worth doing right! So take your time. And ask lots of questions
