Air Canada at YYZ operates entirely out of Terminal 1.

Connection Time US > International is 1:15 (minimum)

Unless you leave the actual terminal building upon arrival at YYZ proceed through Customs Area "B".

Your bags (unless otherwise requested) are checked all the way through -
CLT/YYZ/SCL.

On return flight, bags (although tagged to your final destination) must be claimed at the US pre-clearance area, and placed on the connection belt to your final destination, following actual customs clearance.

All Info can be found on AC's website.