1. Follow the conventional wisdom: Threaten Sealion, typically by building a carrier and transports (OR not spending your G1 income). If the UK decides to play defensively, then go Barbarossa. If the UK decides to be reckless and leaves London undermanned, go Sealion.
2. Italy should try to clear the Mediterranean and take Cairo. Fight the Allies for the Middle East if you can.
3. This depends on too many variables. I wouldn't let either China or Calcutta become strong if I can help it.
Thanks, but I still need a Japan strategy