How long it takes to process this visa?
The average processing time as claimed for this visa is 75 percent of the applications in less than a year and 90 percent processes within fifteen months.
Can I renew this visa of mine even I am not related to the special category visa holder anymore?
Yes, even if your relation with special category visa holder has ended and you wish to extend your partner visa you can do so as long as you have retained Australian residency and have stayed in the country for at least couple of years.
Where do I have to be while lodging an application for this visa?
You can be either onshore or offshore when you apply for a subclass 461 visa.