Ok, lots of issues to speak out here.
On Allied ICs - Japan’s forces are not in a good position at the start of the game. They do not have more troops than the combined allies. They only have 2 transports to the Allie’s 1, 3 provinces to the Allie’s 5 (counting Yakut, India, Soviet Far east, China, and Sinkang). This means it will take time to expand into Russia. The point of the ICs is to make that time harder. If you build 5 tanks a turn (this is the ONLY time I warrant buying so many tanks. 5 Tanks a turn will slow the Japaneese Advance considerably, and will easily overwhelm any Mainland Factory.
On your Indo-China IC. First off, how do you plan to (a) beat 2 ICs with your 1 IC and (b) STILL attack Russia? Enough said.
On Tanks vs Infantry. I remember the first games I played Axis and Allies. We thought the Axis could never win. Why? Because Germany bought 6 tanks a round, Japan bought 2 ICs and 6 Tanks a round, and Russia Built all Infantry. Russia always won, simple because they had far more bodies than than the Axis.
You say Infantry suck at attacking. Listen to this math.
You have 15 IPCs worth of Tanks or Infantry (I use 15 because it is the lowest common denomonator). 3 Tanks attack 5 Infantry. First round, Tanks get 2 hits (I round up) and Infantry get 3 hits. Tanks dead, 3 infantry are left. Attacker loses 15 IPCs, Defender loses 6 IPCS.
Now, 5 Infantry attack 3 tanks. First round, Infantry get 1 hit, Tanks get 2 (again rounding up). There are now 4 Infantry and 2 tanks left. Next Round, Infantry get 1 hit, Tanks get 1 hit. There are now 3 Infantry, and 1 tank. Next round, both have a 50% chance of hitting. Get my drift?
Don’t Believe me? Done with the odds calc found on this sight, The attacker has a 15% chance of winning in the former, and a 64% chance of winning in the latter.
Bottom line, Infantry are better.