I did not want to add everything and bore folk but as you asked .From reading and experience the key factors in battle that I would add are: Ground, Weather, Training (inc Doctrine), Logistics. Morale and Leadership. You allude to a few of these but I think that they should feature more heavily.
Ground, we cover al the basiscs in our own way. What is unique with us in Ground is we have a workable dead ground system although by definition a bit approximate. One of the issues we are looking at in our games (the authors) is expanding the range of terrain we use. Mostly this is just a definition issue. How many types of terrain do you want? The game can have far more than we use and infact we are somtimes guilty of being quite limited to what we chose, that is our limitation not the games. How many folk use wooded slopes of Motorways, these can make it impossible for even tracked vehicles to climb.
Weather the same and of course day and night. However a platoon commander said with the advent of Night vision nighg and day tactics are becoming closer.
There are limits to leadership, morale and training that can be accomodated. A poor player acts as though he is badly trained. The all too prevalent CHARGE regardless of common sence cannot be avoided by rules. Morale - Again lots of folk say they get morale right but I have my doubts. We have a combined Fear Fire fatigue, ammo parameter called Leadership. As it degrades the ability to get the units to act as you would like deteriorates. Lower leaderships are more reluctant to move when suppressed. The parameter can also be looked at as an ammo supply when it reaches a certaon point the troops are nolonger a viable force. Brittleness can be set by the value at which troops cease to fuction. I have no real interest in rabid vengeful souls with no fear or training so we do not cover such folk.
Logistics (amatures concentrateon tactics, proffessionals on Logistics). Most players fight a single battle. so Logistics is not that significant factor if they have what they need at the start. Artillery have to have an allocation of ammunition. Typically what they carry for SP guns. They may have more for a Shoot and scoot but it takes quite a while to reload, or you risk loading from an exposed position, bad news if there is counter battery fire. For infantry see above. Again for vehicles normaly fuel and ammo is not an issue. The authors sometimes play at a higher level where the game can run for 150 bounds on a very long (but narrow board). Look at is a linked set of games with no breaks in the ground. Then logistics becones critical as vehicles need to re-form, re-arm and rest. This adds much to the complexity proably more than most players want. Many 1 stand=1 platoon neglect this entirely but since you are a above a company in action, logistics becomes a key parameter. There was an interesting thread in the old forum on bigger battles.
Doctrine - Interesting as far as I anm concerned that is not a rules issue. If you want to do so use your troops accordingly. Button up regadless and suffer the consequnces both good and bad. As I cannot teach a bad player good generalship, it is beyond me to teach him doctrine. I can give hom forces structured as the requisite structure but practicaly that is all.