Whoops! AY is right. I understand that Icelandair are doing cargo flights into YHZ and may restart pax as well. I believe that they could not offer fares from Canada as low as those from the US due to some Cdn Government pricing rule.

KEF is a decent airport, and a great place to get cheap sweaters. I believe that you are entitled to a free stopover in either direction as well.

As for AZ, that codeshare is slowly winding down. It is heldover from the CP days, but I believe that the new summer schedule will only codeshare on the MXP route, not FCO. And the YUL-FCO announcement didn't mention AZ either. They do not reciprocate with each others FF programs.