From: OH, USA
And to finish up.
A. China is relatively straightforward. Go for the jugulars. The problem here is entrenchment, surface area, rivers, and partisans, in order of annoyance. Probably should have manned the 10 resource hex NW of Qingdao, may have done so in the screenshot. The key problem that can be tackled differently, IMHO, is surface area. Most of your forces are Japanese divisions, which will be hard-pressed to get that 3:1 or 4:1 ratio attacking from 2 hexes. My solution is to exchange 2 divisions with 1 Manchurian army ASAP. This will take a few turns to shuffle and ungarrison, but doing so allows one to press down with two armies in multiple places. Bonus points for getting your armies more experience this way.
B. Railed up a few divisions, moving down cavalry and armies when possible. As long as total ground > 159 strength, you're good.
C. Double Port Moresby landing and blockade of port. Note that you're able to exert ZOC terrain control even in the presence of an enemy unit (is this because it's weak?). Rabaul is taken by an SNLF, which might be overkill, but it's impossible to take the port on the same turn due to lack of a road for 1 OP movement.
D. Various island activities, ranging from single ship blockade to prepping a landing force. It's slightly possible that these can be pursuit attacked, but that will engender a counterattack on the allied ships. Screwed up on New Caledonia and didn't have 3 boats to blockade.
For the island hopping, there are so many permutations that it's impossible to find the best solution, which may be in fact depend on Allied response. Fiji will probably take ~2 full divisions to take, so I don't commit there yet until seeing Allied naval moves, which may involve a PH counterattack.
Production: 3 x landing craft, ungarrisoning a lot of units.
Advancements: (IIRC) carrier, interceptor, naval air, assault, amphibious, long range subs