I don´t know a better link where the MPM (Maximum Permitted Mileage) rule for paid tickets is explained than: http://www.travelterminal.com/glossary.shtml

However, the amount of QG-miles you need for free tickets are based on award zones. For your example YUL – ORD - ANC (final destination) – DFW - SFO (stopover) – ORD –YUL on a free Coach Class ticket on AA referring to QG´s award calculator you need 25.000 QG-miles.