As far as I'm aware:
1) You don't need any other Visa and your travel agent shouldn't apply for one. As long as you are making your first entry before the initial entry date on your PR Visa nothing else is required.
2) You pbuttport will be stamped on every entry into and departure from Australia. Ours were stamped on the page opposite the visa label.
3) On internal flights you won't be required to clear customs therefore your pbuttport won't be stamped.
4) you don't have to do anything. We just enjoyed our holiday and had a look for areas we we would like to live in when we get there permanently.
5)You get a 5 year RRV with the visa grant so you can travel in and out of Australia as much as you want for up to 5 years from the date of grant before you must worry about this. For the exact date check your visa label. Many people say you should aim to be residing in Australia within 3 years so you can get citizenship or a new RRV when the inital one runs out.
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