From my understanding, the CP penalty was a game mechanic to recreate a smaller, better led force, like Lee in most of his victories, defeating a larger, uncoordinated force. So as the mechanic may indicate, the smaller force fires first most of the time. The larger force loses cohesion and takes hits before returning fire amd may even rout without firing at all.
I'm not sure how much the speed penalty is. A faster stack would have a better chance to MTSG. As for retreat...I'm not familiar with the concept.

I'm the 51st shade of gray. Eat, pray, Charge!