Best Mobile Network Provider in Canberra

Hi there, I'm moving to Canberra by end of August from Toronto, Canada. I'm wondering what mobile service provider you guys are with and your experiences with them are like- so I can make a better decision when I hook up to one when Iarrive in Oz.

Also, are there many free wi-fi networks around in Canberra (e.g. in shops, restaurant and public buildings)

Thanks!
Meriam