To answer your secondary question...
I would start by checking the basic fares to from YYZ-DFW for the dates that you are going on a site like Expedia, Travelocity, Orbitz, etc... Once you find a fare you like & are willing to pay, take a look into the routing rules (use the Expedia Fare list - located in the MR Tools thread in the Mileage Run forum) - and see how you can maximize it by adding some connecting city pairs.