Just a few comments after testing some more:
Newest version is pretty good, though there are some textual errors (Great Canyon should be Grand Canyon, and that sort of thing).
Infantry are a little weak still. I'd go for cutting the realism a bit with the infantry, and reduce the number and increase their power and cost. I mean, you do that for zombies, so infantry might as well be buffed to "super-infantry." Instead of a 10 cost basic infantry, make it a 25 cost and buff it appropriately. It seems of most things, it's their damage that's the most lacking. The other way is to make a Squad/Grouping system, but that'll consume player slots you don't have.
Also, a "Load all nearby Prisoners of War" ability would be quite useful on the PoW camp; selecting them one by one is a little annoying when they're all tiny and sometimes blend in with the landscape.
The Fire Battery (should be Fire Batteries) ability on the Iowa Class Battleship should have a longer cooldown and duration, to ease the amount of reclicking that needs to be done. Or, the ability can be changed into a toggleable ability. With the number of units on the field, the less things to micro the better the player will feel.
I was thinking that perhaps players should start with one airfield and one vehicle factory. It seems a little awkward that countries so large have no working factories to start with? I don't know if it'll affect balancing or something, it just seems good and will bring action a little sooner to the game.
That's it for now, I'll probably post more thoughts/suggestions later.