I’ll go in reverse.
Marines: Honestly, unless your opponent forgets you get to transport marines by submarine for one turn and leaves Japan open, I don’t see the utility of them in the long run, compared to the fraggin AWESOME advantages America can choose from.
Tech Investment: By far THE best NA in Enhanced. Common! No more wondering if you get the NA AND you can pass the savings on to friends! (Who wouldn’t want to pay 12-16 IPC per tech instead of 16-20 for the first attempt???)
Reinforced Carriers: Nice, helps absorb hits from the German submarines, but as Bean said, not very utilitarian except to hurt Japan afterwards.
Pac Div: Okay, an infantry is nice. In in a 10 round game that will be 30 IPC.
Naval Industry: Very awesome! Counters Kaitens by giving you the price break, makes it possible to buy loads of fighters to give away to England and Russia, etc.
Mech Infantry: The way to go if you are doing Africa. Inf + Arm = Fast run to Caucasus. Saves you 4-6 transports.
Japan needs a bit of tweaking. For one, Tech Advantage should be identical to America’s NA. Why nerf the Japanese one? They already have the Kaiten and Kamikazee nerfs (lost equipment for possible results.)
Tokyo Express can be a life saver if you are facing a K/SJF. They function just like transports in NCM and like half a transport in CM, but they can bombard if you have CA and they can fight.
Russian Rail: Too powerful. This needs to be scaled back to LHTR restrictions of what zones you can double move your infantry through.
I’d also like to see Africa Corps replaced with naval water tight hatches: you have to detect the submarines and then you have to roll at one less then your normal attack value to sink them. (Destroyers would roll at 2 to hit them.) Might be overly complicated to implement.
Failing that, how about giving Stuka’s their SBR capabilities back? 1d6 / 2. Then if Germany gets JP, they can use the Jets to replace the SBR damage on England that their submarines arn’t doing because they’re all dead. (England, of course, will counter with Radar and their own JP to intercept.)