Screen Placement (compared to viewer, and speaker placement)

It's been a very long time since I posted at AVS, but I'll give you a starter.

1. It sounds dumb, but where it feels comfortable, and allows you to see the whole screen unobstructed when considering the seated position. For instance, if you used a recliner, and liked to go lean all the way back, with size 15 feet, you might need it a bit higher. I have heard the very general ballpark figure of eyes at 1/3 the height of screen going from the bottom, but that's too general. The easy way to do this? Fire it up on the wall without the screen, play around for a while, only using 16:9 material, then you'll know for sure.

2. No, I would not.

3. Yes, that would be better. You don't want a version with "holes", microperfed, because those require greater distance between speakers and screen, to help avoid comb filtering. You want a weave. It can be very, very cheap if you build one with say Seymour XD, or more with a prebuilt frame. However check out the Screen Excellence Enlightor 4K. It will be expensive, but you won't be able to tell at all that it's AT. Well, not until you get close to arm's length from it, or thereabouts. It won't be as bright, but that is not a terrible concern with the modest size screen you have IMO. The weaves like the ones mentioned above need something around the order of only 0.5" to 1.0" between speaker and screen, or thereabouts. OTOH, if you don't want to spend so much for perfectly invisibly texture, I sit closer than you do to my XD, and it's perfectly acceptable to me. I am coming from a previous solid screen using the same JVC PJ too, btw.

4. In wall speakers can be every bit as good as other types. I'm not familiar with your old speakers. The main drawback for you is that you typically pay more for the same performance, but OTOH, you can build your own for very affordable prices. I know that Zaph should have a design for in walls, at the least. Short answer: yes you can probably get the same or better quality for just as cheap if you're willing to build your own. Otherwise, maybe not.

5. If you want to, but it will probably sound like chit. I wouldn't shove a speaker in a corner like that if I were you. You're "not an audiophile", so it's your decision to make, but then, I guess you're still asking for a reason.

The above are my attempts at giving my personal answers to your queries. I now take the liberty to say that the first big improvement you could make to the HT experience, from the audio perspective, is to reorient it all lengthwise with the room. Many many benefits. Axial modal issues, then heads no longer up against the wall (you actually don't need several inches, it's more like several feet) where the muddying bass will overwhelm your midrange/HF, and your audio will be more balanced left/right as you don't have the significant SBIR of the left corner loaded speaker, etc. The left wall acting as reinforcing boundary, well I'm sure the issues you have with left speaker will be duplicated by left and/or left/rear surrounds as well. That's not even mentioning placement issues.

Good question. Someone else should really answer this, as in, someone who knows what the hell he is talking about.

My guess is that the inwall would be a tad bit better, as far as not requiring any rearward space (rear wall energy isn't compounding/multiplying the sidewall energy). It is like the concept of "infinite baffle", and therefore in wall speakers do not have BSC (baffle step compensation) designed into them, there isn't that need.

However, you still have that early, and extremely strong sidewall reflection. Would you be fine with a big mirror, adjacent to your display, making a right angle with it? Probably not. Is that an exaggeration? I don't know. But, you can pretty much bet that your left side will sound both louder, and different. You cool with that? You can help greatly reduce this issue with loading it with lots of broadband absorption, but YMMV.

Speaking of the possibly exaggerated analogy, every time you get a bright scene, fiery explosion, if that wall is light colored, it will brighten up every time. Even flat black paint will brighten up. It would be weird to use expensive telescope grade velvet on that wall I suppose, but even then, you may discern some reflection for how close it is, and how close you are, mebbe. Remember a projector is like an extremely high powered flashlight.

So- lengthwise orientation would not only balance your audio out much better, both lengthwise and side-to-side, but would likely improve the visuals too.