I have gotten in touch with JaM, and he very graciously told me how to make it so that only two ranks fire. I will look into putting this into my mod, since I too would prefer the more historic firing methods.
I have not touched musket kills rates. Projectile kill rates are left at CA values. All I have done is increase range.
Not that I am aware of, but to do so I would imagine would require editing the startpos, and I have only seldomly delved into the startpos, but that is something I do hope to correct in the future.