@gn0m:
In my experience, US can enter Asia almost at the same time as Japan if no pressure is put upon the US. Is this true or can Japan focus on Eurasia and still delay the US, and if so how? Should Japan build an IC on the mainland and if so, during what circumstances? From which direction should Japan go when invading the mainland, through Russia, India or China? And a bonus question; is it worth the time/transports to get the Japanese infantry that are spread out among the islands and transport them to the mainland?
Not sure what you mean here…are your opponents approaching Asia from the Pacific?
In most games, it is a good idea to capture Aussie, NZ, and HW asap. If possible, you can harass the Americans in Alaska (typically after these islands are captured). But in reality there are far more IPCs in Africa, so if USA is going whole hog for Germany, you can turn the tables my using mobile transports to get troops to Africa.
Meanwhile, your primary focus (ie 95% of your resources) should be aimed towards Russia. Buy up to at least 5 (up to 7) transports…4 for unloading troops off Japan, and 2 more for capturing islands and Africa. If the game is a KGF (ie the Allies are fixated on Germany), I wouldn’t recommend a mainland factory until the 3rd Japan turn.
But bear in mind that strategy depends on what your opponents do. You may want to put down mainland factories sooner if Russia is weak because that will enable you to put tanks on the ground faster. And if you cannot protect new transports (say, usa air is threatening), obviously you have to hesitate before buying them.