AlextheGreat, looks pretty cool!
I see, the "multiple arrows" animation looks like the arrows were fired also simultaneously as I noticed on the screenshots.
Just to clarify what I think Carl the Great was saying, you can give models multiple projectiles. See
Multiple Projectiles for more info. This lets your unit (I assume your grouped soldiers are units) fire more than 1 projectile. The position the time which each projectile is fired can be offset, which will make it look like each unit is firing an arrow.
There is a way to determine the number of units of an army, the code allows multiple G3Ds in one skill depending on how much health left, just like when a structure is being built or attacked by an enemy over time.
What I think Carl the Great is referring to here is megaglest's extra
animation features. If you follow the link I have just given, you can see that animations can have the parameters
minHp and
maxHp. This is the health range for which a given g3d model is displayed. The idea is, you can link multiple g3ds to the same unit, and you can set boundary conditions for when these g3d models are displayed. e.g. one of your "units" might be 10 archers. You could make 10 g3d models, one of them consisting of 10 archers, then another consisting of 9, and another with 8... etc. Then, you can configure the unit in the xml to display the g3d with 10 archers for 900 < x <= 1000hp, 9 archers for 800 < x <= 900hp, 8 for 700 < x <= 800hp etc (x is the hp/ health of the unit).
I you want to see a good example of this g3d-hpbound-model stuff, download the ultrapack mod in the mod centre, and look at the file: ultrapack/factions/crusaders/units/defense_tower/defense_tower.xml.