A tax file number is what employers use to pay tax on your behalf by automatically taking a bit out each pay. You will generally need one to work - with the exception of a few cash in hand type jobs. http://ato.gov.au
is the place to go for all tax related information. Their will be offices of the ATO in all capital cities.
As for the bank account, you have a few options. As a recent arrival (for the first few weeks) I think you're able to open a bank account at the bank using only your passport and entry visa as Identification. I can't remember if you are required to be a resident. I notice you live in the UK - there is a branch of the Commonwealth Bank (one of Australia's major banks) in London where you might be able to enquire or even open an account before you get here.
Getting a sim card will be very easy. Prepaid sims are sold everywhere - just look for a phone store. In all likelihood there will be one at the airport. They will work with your W800i.
Plenty of jobs going around at the moment. If you're in to earning a very decent pay for manual labour and want to see the country, the mining industry is a great place to pick up a job. They'll often do fly in/fly out to a nearby capital and put you up with food and accomodation when your onsite. The downside to this is when you are on site the hours are long and the work is hard. You do get paid very well though - in the order of AUD$80k+ pa.
Other than that, depending on your skills theres always bar work as you mention right through to things like fruit picking.