The interviews here are very structured. Two interviewers, pre-set questions. I came here to interview at UQ, USyd and Flinders a couple of years ago. I don't remember bringing anything to the interviews themselves except my letter of invitation, an ID and my suit. The format will be similar whether you're interviewed in Oz or in Canada, but I don't know how they might modify things for phone interviews (never did one).
UQ (still) does a bit more outright 'testing' than the others, like picking from a list of technical terms and explaining two to a non-tech person. They also have a number of positions that you're to choose from and 'argue' for one (testing your ability to advocate and persuade without being a jerk, listening skills, respecting others' opinions when the interviewers play good cop bad cop, etc...i argued that the UN was an anachronism, to show that as an American I could do this without being boorish). They'll also tell you a story, w/ third person versions of the events, then ask you to paraphrase it. They're looking for comprehension and objectivity, e.g., saying "John thinks that Sara cheated in the game..." rather than "Sara cheated in the game", stuff like that. Oh yeah, my year they asked what the challenges were in aboriginal health -- just think Native American health (obesity, diabetes, alcoholism, domestic abuse, the socioeconomic/cultural issues, yada yada).
Sydney was more rapid fire of more standard questions, with few follow-up questions -- what are the biggest challenges to medicine, what is the place for alternative med, what's your biggest strength and weakness, how do you plan to pay for med and what do you plan to do after graduating.
Flinders was the most laid back and personable, an actual conversation with the interviewers. Not that it was any less structured though! It started with being given a scenario (pre-written) that you're to think about for 10 minutes, then use the whiteboard to explain. That was an excellent 'test' I think, and along with the homeyness made it the most fun interview I've ever had, ever (it helped that we were joking around for much of the 90 minutes).
In general, all are looking for thoughtfulness (showing you've thought about your career choice and what you're getting into), ability to listen w/ out interrupting and to explain/paraphrase/communicate effectively, respect others' views, etc. They have score sheets for assessing you on such traits! One tip: where appropriate (on the 'tests', such as when defining the technical terms), use examples or analogies.
Here's a site that has others' interview experiences at several of the grad schools:
http://gmp.steinerfamily.com/
-pitman