some other things that have popped into my head...
The visa rules are important to check, if it's employer sponsored what happens at the end? can you get residency (if you want to and your enjoying it) - it may also (probably) cover NZ
If they are offering to relocate check the leaving clauses, could be the longest notice period you have ever seen if you need to pay back shipping etc.
What are the chances of moving with the company? Start in Sydney but have most other State Capitals on offer?
With the current state of the £ you would probably be better off shipping more of your stuff over rather than trying to buy here with any £. Don't go shopping till you have some $ in the bank. It is creeping back but it will be a while before it's back up at 2.5 again.
Fuel tax is low but driving in sydney is a bit ambitious. Also finding economical cars can be harder but due to the crap £/euro EU cars are getting cheaper!
Alcohol tax is higher
Property is demand driven but as above not well insulated etc.
For the important stuff there is a lot of bike stuff going on in NSW, it's 6hrs to NZ (I'm off next week for under $1000 rtn) you can get to Cairns (currently winter & 26c), Tassie - winter mountains or the NSW snow fields fairly easily & cheaply for a weekend.