A.) I have not been invited to any other large mods development, no. Would I be interested in it? Maybe, but if I began helping out with a secondary project, I would most likely try to handle macro-level battle mechanics balance on that team.

B.) The KV rules files have some variables focused around giving units armor bonuses based on projectile range. I still haven't perfectly learned how to use them, however.

C.) There is a pierces shields tag. Currently, no shield attributes are used when blocking artillery fire. The current penetration tags are ap, low, medium, and high. Only medium and high are used in Attila, and I have seen AP used in shogun 2. However, it may be that the projectile category is where missiles get their ability to ignore projectiles. I guess what I could say is. "There are a lot of potential sources of penetration abilities, but it would take time for me to bring it down to a science."