YKF has no pre-clearance FYI, so you land in ORD Int'l terminal (T5?), at least you should get in quickly via Global Entry
but YKF is super small, very easy/quick between check-in/security/boarding
Also, you can redeem 4500 Avios one-way on AA (American Eagle) instead of cash fares
YKF/YYZ-ORD 4500 Avios + $60