1. Depends. If you're politically compatible, play ComChi :rofl: If you're a nationalistic flag-waver, try NatChi.
The real difference: ComChi gets better leaders, a small but high-quality starting army, and helluva fight. But it has a really small area, crappy tech teams, and a smaller claim area (no Mongolia and Tannu Tuva, meaning you shouldn't/can't pick a fight with the USSR.) NatChi on the other hand, gets generally very crappy leaders, a larger but badly-trained army, warlord puppets (whose use other than guarding coasts is next to nil), and helluva fight. It has a crappy but large list of tech teams, a larger claim area (but not Hong Kong or Macao), and nothing beats driving out the Japanese in 1938, allying with Germany, invading then releasing Indochina and India by 1940, punching through the Bolshevik underbelly in 1941, completely (letting Germany) annex USSR by 1942. But what to do for the next 10 years is a problem... Invading the Japanese Home Islands? (Done it before) Conquering all of Asia? (Feasible but too lazy to do it), or WC? (Navy a problem, Germany really tough.)
EDIT: 2. Forgot there was a 2, got too carried away answering 1! OK strategies... for NatChi, do not destroy ComChi before the Sino-japanese war. Their superior divisions will come in handy, though don't fight your entire war with them. You'll need to whack them later on. For doctrines, use infiltration instead of (the stereotypical, and inaccurate) human wave. After the war you can ally either Allies or Axis. Doubt the Comintern would want you. But why be Allies when the nearest Axis country is half a world away? (Japan n/a, stupid sea) so let's be Axis instead. Whack the Brits (and frogs) good. Build up a navy, haven't tried this in DD but subs should be a bit less overpowered now, so maybe building superstacks of SS would not be the best naval tactic... :wacko: From there on the world is your oyster. You're now a major power. Hurrah! Invade USSR, or sit tight and upgrade your infrastructure (you've got 10 years to waste!)