Nope only if you enter international waters – but check with the cruise company to be on the safe side.

I would say no but best to check just in case!

pretty sure that you don’t need a passport while on that ship.

You will only need a passport if you go into international waters. When you book your cruise, the booking company will let you know

Travel agents should provide you with this information and it should be on confirmation travel documents too.

Passports are only required for overseas travel. Check with your booking travel agent for reassurance and confirmation,

I shouldn’t think so.
Passports aren’t needed to travel to Tasmania so I would think not.
Double check with your travel agent to be safe though.