Besides simultaneously movement, which is the big one, we also ‘relax’ the combat-move vs noncombat-move/unit placements. We typically move everything in one swoop. So when the Japanese player is done, UK is already complete save a few battles.
For optimising simultaneous movement, we do this:
- German player do the Eastern front first. This enables the Russian player to move.
- The Russian player moves his Asian units first. This enables the Japanese player to start moving…
- Etc.
Regarding looking things up, I highly recommend creating one-page/double sided “alliance charts”, which have everything in one place. As you start using expansions, it’s a nightmare to organise stats, capabilities, special-abilities etc.