It's vry simple ! you have 2 ways : 1. Use your Uni and go to AUS wwith Student Visa and apply for immigration from inside AUS. It has many advantages. 2. Not to take many risks and go on your own plan , graduated , have a baby and go for work but apply for AUS immigration VISA from outside AUS. It ...

The time depends on many factors.

Your case complexity , your nationality , High Risk or Low Risk country , documents needed , ...

Just visit http://www.austimeline.com to find an estimate yourself.