I certainly don't have an issue with general public owning firearms, however there are a lot of idiots out there... and that's the part that scares me.
For quite a while, the Oz gov has been making it harder to obtain a firearm license as well as own firearms. For general public living in metro areas, I believe that you must be a member of a local gun club, must be endorsed by a member of said gun club to hold and highly encouraged to store our personal firearm/ammo at the gun club in their safe. For people who live rural, there are less restrictions on ownership providing your total land area is greater than 10 acres. (varies from state to state).
IIRC, the current restrictions are no-full automatic weapons, some semi-automatic weapons are banned, and no military rifles either.
While there are firearms available on the black-market, they are very hard to come by, so we don't see a great number of firearms on the street.
Most house invasions are done without firearms, and AFAIK under current law, you may only use the same amount of force to repel an invader for self-defence reasons. So if they use a base-ball bat as there weapon, then that is all you are allowed to repel them with (eg a blunt instrument). It's a very grey area of the law, and the courts hope common-sense will drive each case on a case-by-case basis.
PS. My second last day at work, before embarking on 3yrs of fulltime Uni! Well, it's only going to be 2yrs, as I was offered a job last week which I have accepted, but the position doesn't start for 2yrs. (It was an offer I could not refuse).