Unfortunately, the one golden rule is never take advice from immigration. I know it sounds odd, but they aren't qualified as the people you speak to on the phone are just call centre staff. Hence, they get a legal indemnity for bad advice. We see incredibly poor advice given by them. Hence, the official advice and one that the forum recommends is to speak to a registered migration agent
Yes, people do, but they don't announce their intent as there is even a risk of them being turned back at the airport if immigration are not satisfied they are teeing as genuine tourists.
Your husband and child being Australian will have no positive bearing.