As a *G you'll get E+ for free at booking. DO NOT pay for it, it is almost completely worthless on the 747. It's only worth it if you are well over 6', otherwise I actually prefer the back of E- which is less crowded (and quieter, the flight attendants don't go through there as often.)
In terms of upgrades to biz, I wouldn't bet on it. Here's my predictions:
* Monday - Wednesday: 65% chance
* Sunday: 60% chance
* Thursday: 45% chance
* Fri/Sat: 30% chance
Friday and Saturday are basically impossible unless you're 1K.
If you can only upgrade one direction, upgrade the return. Most of the flight is during the day, so it is much more difficult to sleep. The flights to Australia leave very late (particularly if you're coming from the East Coast), so it is much easier to sleep.
-- Dan