Hi! I really like the idea of simultaneous turns, because many people are not ready to play an 8 hours or more game! :)
Hovewer there are too many rules you created, and i think the capabilities of attacking together is too much powerful for the allies.
I make a soft version of this rules for A&A Global:
SIMULTANEOUS TURNS
The round of play is devided by macroturns, who are played simultaneously by different allied powers. This rules are ideal to fasten up a 4 players A&A Global game.
ORDER OF PLAY:
1. Germany, Japan
2. Sovient Union, United States
3. United Kingdom, China
4. Italy
5. ANZAC, France
Conduct Combat Phase:
Is possible that during the Combat Move Phase more than one power has attacked the same enemy controlled region. If this happens, you have to conduct different combats in sequence. You have to start from the first power mentioned in the macroturn, and then proceed with following power if the enemy was not destroyed. For example Soviet Union combat happens before United States.
If the defending enemy is defeating, all the powers with alive combat units in the region are elegible to be the new controller of the region. All the powers involved must find an agreement together. If they’re not, first power mentioned in the macroturn with alive units takes control.
Non-aggression pact:
Because of their non-aggression pact, Japan cannot decleare war to Soviet Union on his first turn.
See ya! :)