Greetings! I the other way around, I first started playing Supremacy 1914 and then discovered Call of War, however the latter I didn't like so much as the interface is very faded which makes it look somewhat boring. On the other hand it lacks improvements to its game mechanics.
I completely agree that they should add other units to Supremacy 1914, however we have to be coherent since as the name of the game indicates its events take place between 1914 and 1918. By this time there were not many models of aircraft, there were few models and very rudimentary as they were just beginning to be used for war purposes, although if you can add another model of aircraft with other purposes in the game, for example a plane that can launch incendiary rockets Le Prieur, these rockets were used to set fire to the spy balloons, barrage balloons and others. The barrage balloon can also be added as a new air unit, these were used to protect cities from aerial bombardment.
2 ) Naval: Aircraft carriers cannot be added to Supremacy 1914 since the first aircraft carrier in history entered service in 1919, just after the end of World War I, so this ship was not used in this war.
3 ) Terrestrial: In terrestrial units if it is necessary to add an anti-aircraft unit, these already existed in the first world war so it would be historically correct to add it to the game. Other land units that can add is the heavy artillery gun M GerΓ€t 14 which was used to destroy the fortresses and had more destructive power than the MΓΆser M10, they can also add mechanized infantry to carry out the Blitzcriegz with greater speed and effectiveness.
Your proposal #6 I fully support it, constructions and maintenance of units should not be based only on oil, that should be fixed as it is unrealistic.
Proposal #7, I agree with you!
Proposal #8 no, personally I think Supremacy 1914 is fine without doctrines, this gives it the essence of being Supremacy 1914, also all players can access all the equipment the game provides.
#9 I didn't understand, explain this point better.