Hi,
If you are just mounting on wall or ceilling and not
in ceiling, how do you like those B652 Air's? They're about as high value per cost as you can find since they're a fair speaker for $25 each which is really nuts when you think about it. Plus they're sealed so no port stuff to worry about and they are competent with 6.5" drivers and the updated tweeter. If you just want value, these sound good and are as cheap as you can get likely, new at least.
Do you need an amp or do you just want an amp? Looks like your listening position is very close to your speakers, they probably don't need 5~15 watts tops at loud levels near you like that. Your upcoming AVR can drive all your speakers. Instead of a costly amp, I would argue for better subs. Or I would argue just for better, more efficient speakers rather than pay $2200 total (AVR + amp) to drive value speakers and stuff. I'd suggest opposite, spend a bunch on good speakers and then just have enough to drive them with headroom/transients/dynamics and you're set. Just an opinion.
Settings depends on the content. You may want to upmix legacy content. You may want direct on some content. If you want to use your surround on everything you send to your source, well, you'll be using an upmixer which is a big part of having the AVR too. So just go through all them with different content and see what you enjoy the most. There's no default, it's preference.
I see room treatment!
Very best,