If you are a Non Resident Indian (NRI) with a bank account in the country, it is advisable that you are aware of all the existing tax rules as far as NRIs are concerned.
It depends upon your age, marital status, and whether they are citizens or permanent residents.
It will take at least eight years for either category. You can determine your situation from the Visa Bulletin here: http://travel.state.gov/visa/bulletin/bulletin_5953.html- Ed
Australian immigration requirements are very straightforward and immigration procedures and approvals are completely honest - you either qualify for an Australian visa or you don't. NO agent can get you a visa that you wouldn't have been able to get by your own efforts and NO agent can get you a visa any faster than it will take you if you do everything yourself. Most people don't use agents and many who do find them not to be worth the large amounts they charge.
If you are absolutely determined to use an agent, make sure they are MARA registered and that the company they are working for is MARA registered rather than simply sub-contracting out work to registered agents.
https://www.mara.gov.au/ MARA
Before you commit to anything, you should join the Pomsinoz immigration forum and ask your question on there. PIO is a very busy and helpful forum and someone on there is bound to have first hand experience of the agent in question or can recommend another agent in your location. You should also inform yourself about the immigration requirements that will apply in your case so you know what questions to ask your agent and so that you can check what they are telling you. If you want an indication of the likelihood of your being able to get a visa, you will need to provide details of your occupation, qualifications, work experience and age - post that info on PIO or on here.
http://www.pomsinoz.com/forum/migration-issues/ PIO- Ozmaniac