Be wary when making house rules what your “historical accuracy” does for gameplay.
None of these three are very well-defined and bounded, leaving them open to mistakes, rule-disagreements and abuse.
For example, can I negotiate with my ally that in return for sending one German airplane squadron to help against China, I will get German control of a factory on the Chinese coast? Quite the game changer if suddenly Germany can build in the Pacific! Or better even: can the Brits have an agreement with the USA that if they build a factory in Egypt and the Americans help defend it they get to take control of it?
And what is a ‘Capital ship ability’?
So, in short:
Number 1 just adds a whole load of fiddly upkeep stuff to an already long game, and significantly weakens China.
Number 2 breaks the game.
Number 3 is not needed, nor historically accurate, nor improving gameplay.
Nice starting point if you intend to make houserules: https://www.axisandallies.org/p/five-tenants-good-house-rules-axis-allies/