Drop Unit Design in favor of Army Deployment
Forget unit design. Elemental should commission armies in stages. First step -requisition troops- from the population. This first step should take a set amount of time. Once requisitioned troops require upkeep but on a limited basis if not mobilized. Second step -train- troops. Training time should increase at an appropriate rate to institute deminished returns while maintaining the unlimited research model. Final step - equip/mobilize - army. Equiping an army should be as easy as looking at what's in the warehouse at the moment. This prevents the missing equipment in unit design problem.
I believe this would alleviate some equipment problems that have been discussed and add some role playing features. Now you are no longer naming a unit template but you are naming armies. These armies gain experience and can return to the armory for better equipment or additional troops in their home city or another. This also makes looting enemies more practical. Also the army could de-mobilize which would return their equipment to the warehouse and reduce their upkeep. Finally, I believe this method more accurately mirrors armies throughout history. Thoughts?