Toronto can be a rather tiresome place to connect. Expect lots of walking, checkpoints, rather muddled security arrangements, and as Kate_Canuck has pointed out, zero queue jumping for F/J or elites. Queues are generally minimal though.

That time is fine, assuming nothing goes wrong with your AC flight. If it does however, as you know, you will have limited options with BA if you miss the flight as AC is a separate PNR and a Star airline.

Not sure on the bag, my connections through YYZ are usually heading to the US, which requires re-checking the bag. Sure someone else can advise - try the AC forum if you don't get an answer here.