Well according to page 49(starting there) of the manual, your posture is very much dependent on the type of terrain you are in and the amount cover and concealment that terrain offers. Additionally, the type of movement order dictates how your units will act during the movement, bounding, and overwatch, in attack formation or column. Order delay is a function of if your units are engaged and if your HQ's are under fire or if a higher HQ has been destroyed and whether a subordinate HQ is now taking overall command. I agree that combat resolution is a blackbox process, but I believe that I read on the Slitherine/Matrix forums that they have extensively researched weapon performance and established some algorithms that take into account weather, the terrain in firing and target hexes and readiness levels, ammunition levels, etc., and you have to kind of take it on faith that they know their stuff. But given the operational scale of the game and units, I think the game engine does a good job of combat resolution.