Greets!

L = liters, ergo the cab's net internal volume (Vb) = 320 liters after the driver's and any bracing, venting bulk is deducted from it.

Right, a cab that is 'V' shaped when looking down on it. What angle you choose is up to you, but most are ~90 degrees included or a little more to fit in a typical nominally 'square' room corner.

??? How could they unless you intentionally turn them to face each other. Do the ones in the link I posted face each other?

Regardless of cab shape, how you position them in-room depends on what sounds best to you, though typically with most compression horns, aiming the left speaker at the far right listening position and vice versa works well or at least is a good starting point for experimentation with them firing at the opposite corners being common in long, narrow rooms.

The main thing is to not have any early reflections in front of the listening position above the ~500-1 kHz BW (band-width) depending on what sounds best overall to you WRT depth/width of sound-stage and vocal clarity.

How should I know if your room/system will create what you consider a 'wide enough' sound-stage?

As a general rule though, compression horns will generate a much deeper/wider sound-stage than a typical cone/dome speaker due to horn 'throw' and much greater directivity control in our critical hearing BW, but again, if you're expecting any but the most lossy constructed small room to sound like a large hall or even a large piano bar, then you'll need one of those processors that can create synthetic Hall, Concert, etc. special effects.

GM