From: Northwestern Georgia, USA
Hey, you're the commander in chief, so you decide! That's the fun of the game. Make your best guesses, learn from your mistakes and successes, and have fun.
To answer your questions, briefly:
1. Up to you about Lex and Ent. Enemy subs are a danger. Enemy carriers could be, too, if your opponent guesses your destinations. And watch out for sending ships to Oz or Indonesia, as fuel can become an issue (Indonesia has plenty but sometimes your TFs will find the route closed and they'll be low on fuel when they do so).
2. PoW and Repulse might do best to hole up for a few turns or a few weeks, hoping to hide while the vortex swirls about them, then make a break (for Capetown, not Oz) when it seems like the enemy's forward forces are out of ammo or retiring to replenish, if such a window occurs.
3. Rangoon can become hot early, due to enemy fighters and bombers at Bangkok or vicinity. Very early, sometimes you can get troops in, but be careful.
4. You can slow your opponent by posting troops in the jungle/good defense hexes south of Rangoon and Pegu. Most of your troops are poor and mostly they can't stand up to Japan. Your bombers and figher bombers can selectively target advancing enemy units. Against a good and experienced opponent, the best defense is simply knowing he has to advance via bad roads and that his units may suffer for supply. Once he sends major TFs around Singapore or around Sumatra, all bets may be off. So you'd better also attend to your deep defenses, as at Madras, Calcutta, Chittagong etc. You don't have nearly enough troops to do these things, so be careful if you decide to fight forward. You might end up regretting it.