I'm sorry I didn't get back to you sooner, I've been working on something else
Dogstarsleddogs gave you very good advise. Mals are a different breed, definately not guard dogs, they more likely to let a stranger in and show him the fridge, that way he gets a reward lol! Many say that females do not get along with other females, many breeders I know keep their females in seperate kennels. They are a very affectionate, loving breed and everyone's friend.
I would suggest making an appointment and asking if you can take your dog with you to see how they interact. Your Aussie is a herding instinct, and Mals have a high prey drive, especially for smaller animals, so keep that in mind.
Adoption is a very personal decision only you can make, so I'd never assume to tell you to go ahead or not. The best advise I can give you, is read all the info you can on the breed, talk to as many as you can, and learn both the pros and cons of the breed before you decide. Malamutes are very determined require alot of grooming, and persistant guidance throughout their lives. They are not popular for obedience work, although you will find some examples, so if you're looking for a dog that will always come on command, for example, a Mal is not for you.
A breeder once told me that a Malamute lives WITH you, not FOR you! Sorry I can't be of more help, but ask away if you think of anything and I'll try to answer for you. BTW, is your home air conditioned or do you have ALOT of fans, and how do you feel about miles of tumbleweeds in the house when they blow coat?