WiFi/Airtime?

The iPhone may not be the best choice for you. The iPhone will use 3G or Edge when it cannot connect to a wifi network. For example, if you decide to watch Youtube on the schoolbus, that will be a data charge. You decide to look up when a movie is starting on the sidewalk, that is more data.

Some places have lots of wifi hot spots and others don't. I can use wifi if I'm at Starbucks but if I go to Burger King, I have to use 3G or Edge.

Are you talking about minutes or data?

The bottom line is most apps use data and most apps can get their data via wifi but if there is no wifi, they will default to cellular. SMS is one app that cannot use wifi and must use cellular so if you text a lot, you'll be using cellular but I'm not sure how Canada treats texting from a cost standpoint. I suggest you go to you iPhone provider in Canada and discuss this with them.

There is a huge difference, minutes are used when you talk on the phone and data is used when you browse the internet, download things, etc.

If you are worried about minutes you can download an app like skype and use VOIP over Wi-Fi because skypes minutes will be a lot cheaper than your carrier.

I was asking what you are worried about, using data or using minutes.