Some thoughts about posleeen.
Grunts - Extermely high morale, very low experience, weapons with extremely low accuracy but uber RoF.
Squad leaders - Extremely High Accuracy, Very High Morale and exp. Tenars (or what their vehicles were called)should be armed with SAMs with very high range and accuracy, and equivalent of US 120 mm cannon (simulting plasma weapons)for ground work. They should have armor of 1 (50.cal snipers were able to destroy them) have superior stabilisation and fcs ratings.
For tenars and posleen flying tanks, you are using helicopters class, right?
Anyway, are you thinking about modelling earth's Mobile Infantry too? I think that each MI trooper should be modelled as independent unit, like light tank or something
. Platoon of MI wold be company type unit in game terms.
And last thing - i don't think posleen normal shotgun would be similar to humans. I'd say it would have much more power.