1) If you don't have "easy experimentation" then the questions you ask may be moot.
2) If you can, check with Clayton as he should know
3) Optimum distance for bass is variable depending on room dimensions and listener position, but if those positions are fixed or limited, then you may be stuck with what you have.
4) Same for sidewall/midrange--you have to be able to experiment
5) Rake angle, my guess is, not recommended with "controlled directivity"
What I use and suggest are Shakti Hallographs, or DIY them like I did, I can send you a link from AudioAsylum.
My experience is that (depending on the recording mike placement) I find myself wanting either more soundstage, or a smaller soundstage. Where the instruments are tighter--piano, if it sounds diffuse then I want to toe the Hallowgraphs in. For me, these are indispensable--they affect bass and midrange a bit, so they are not specifically for bass/mid amplification, mainly, they affect the soundstaging. Hope this helps, good luck!