(this is really long winded so theres a summary at the end you can jump straight to...)
I dont mean to step on anybodies toes but i might just try to clarify process of transfer of registration and getting insurance for you...at least whay you'll pay in sydney.
bikepoint.com.au and tradingpost.com.au and are two good sites to find bikes. the guide to bikes bmbiker is refering to i think is called 'motorcycle trader' and is available for a few bucks every month in newsagents all over the place (as is a printed newspaper version of the trading post).
if you want motorcycle stores all close together head to Church street in Parramatta on the west side of sydney. here you'll find (from memory) styos called Action motorcycles, motorcycle accsessory supermarket(?) and Bikebiz...all of which im pretty sure have websites too. (try adding a .com.au). alternatively there is an action motorcycles and a motorcycle accsessory supermarket ra few doors appart down town...i think on wentworth avenue (ill have to double check that for you).
The compulsory insurance is known as a ompulsory Thrid party Personal (CTP or as its known colloquially, a Geenslip) which covers damage to people not property. This is paid prior to (re)registering a bike(or car) and will be transfered from the previous owner when you transfer registration. It is renewed every year (with registration) on what ever date it was started-->. when your looking for second hand bikes they will often advertise the date the registration (and greenslip) expires. This is when you will have to renew it. obviously if the bike has a full 11 or 12 months left you the bike will cost equivallently more than if it only has 1 or 2 months left. You wont have to 'renew' the registration or greenslip until that date.
You will however have to pay to transfer them from the previous owners name to yours. The rego is transfered at the RTA (roads and traffic Authority) which are scattered all over the city. The cost of this is largely determined by how much you payed for the bike. looking back at my reciepts from 2004 for a bike that i payed $3800 i payed $23 for transfer and $75 stampduty = $98. I cant remember if you have to transfer the greenslip through the insurer separately or not...The RTA will let you know.
As bmbiker said the forms for this will come from the person you buy the bike from.
when the rego does run out... you'll need to get a 'pink slip' (in Sydney), which is a basic inspection by a mechanic which costs $17. you then take this to which ever insurer you choose and pay for the CTP-agian it depends on the bike but if your looking at an XR600(nice!) it'll be similar to mine (XTZ660) which is $360.
then if you want you can get either Third party property or Comprehensive insurance. These are optional- the former covers any property damage not including you own (eg your bike) should you cause an accidant (touch wood), and the latter covers damage to any property including your own. Theres BIG variation in comprehensive prices for this so shop arround.
Once you've got your pink slip and greenslip you then go to the RTA to pay your registration which will set you back around $98...stick the tag in the holder next to the licence plate and your done! sounds like a hassle i know and well...it is. but remember when you first buy a bike it'll still have some time before the rego expires so you will only need to transfer the rego and greenslip then if you choose get optional insurance.
Im not exactly sure about transfering your motorcycle licence over to Australia. I dont think it should be too much of a problem...it will be done at the RTA as well...knowing the RTA they'll charge you then add on a stamp duty (after making you wait in a dirty big line of course
. they have a website too http://www.rta.nsw.gov.au/
1)Transfer rego and greenslip(CTP) at RTA = depends on price (3%) + a fee = 100 to 300 (roughly for a 2nd hand XR). (transfer your licence too!)
2)get optional insurance at insurer = BIG variation. (Yellow Pages)
3) when rego expires -Pink slip = $17 at mechanic
-greenslip = $330 (roughly) at insurer
-rego = $100 (roughly) at RTA
4) optional incurance if you want it.
There is a 'market' value for all vehicle however in my experience it doesnt really reflect what they sell for. get a feel for what is a good price by browsing lots of adds at bikepoint.com.au etc.
sorry this is so long winded, hope it helps,