I applied to Flinders. I really liked the program from what I've read, however I withdrew my application because I have been accepted at Wollongong. I really feel Wollongong is a perfect fit for me.
I unfortunately do not know what numbers are competitive there, but I have a feeling that like other Australian schools you need at least a 24 MCAT and a 5.5 GPA (not sure what the North American equivalent is exactly). I believe the GPA is weighted more towards your last years of study.
Also, as with many Australian medical schools alot of the North American cohort will be from Canada. As for U.S. hospital affiliations, I don't recall them listing any, but they have had successful alumni that have made it to the States. Some are members here on SDN.
On their MD webpage there is a recent graduate highlighted (Felicia Hui) who is now at Greenwich Hospital.
Sorry I couldn't be more helpful, but hopefully other more knowledgeable people chime in.
Cheers!