Just an idea of how you can do the Empire:
on infantry tab, you can have each reg called "Empire state troops" each being a different state in the empire, with changeable weapon choices, eg spears, halberds, sword & shield, crossbows, handguns ect.
Keeping in the infantry, have a slot for empire free company and another for empire archers since they don't have much of a colour based uniform.
Cavalry you can have Reichsguard knights, Knights Panther, Knights of Blazing sun ect, and ofcourse a unit called Pistoliers/Outriders, which have a selection of pistols/autohandgun.
For the specials tab I suggest you have Arillery (of course
) Wizard unit containing Jade wizards and Bright wizards, and Altdorf college of Engineers for sappers.
Hope this layout suggestion helps.