The most useful question is how each agent would price your specific home, not the city in general. An agent quoting the Saskatoon benchmark of $444,700 without adjusting for your neighbourhood, your lot and your improvements is giving you a citywide average, not a valuation of your house.
Ask each candidate what they do differently for a home with unpermitted work or decades of updates, since that is where online tools and generic pricing fall short. A hand-reviewed walkthrough that documents the actual condition should produce a materially different number than a desk estimate.
Commission itself is negotiable and often tiered, a higher rate on the first portion of the price and a lower rate on the balance, so it is a fair question to raise directly with each agent rather than assume it is fixed. Get your hand-reviewed valuation from Joel Dyck.