[Mish]

You should probably see if she can get a work and holiday visa. Work and holiday visa's from Turkey are not the same as other countries - they have a limit of 100 per year and they need to be nominated by the Turkish government: Work & Holiday Visa

Do you live together in Turkey? If she comes to Australia and you marry in Australia you still need evidence and it is recommend to live together for at least a few months before lodging your visa.

 

[Mish]

Yes you can as long as the visa does not have a no further stay clause on it.

Also you will need to be de facto for 12 months or register the relationship to apply on de facto grounds.

Just make sure you have proof of living together ie joint lease, joint bills etc.