A C Zoom

ATM: For withdrawing money, ATM is best, withdraw the largest amount you can, and need, to offset impact of the ATM fee. Limits are usually $500 or $1000 and this depends both on the bank owning the ATM machine as well as the bank where the account is kept. For lowest fees, use the numerous Desjardins ATM kiosks seen all over the city - this is a cooperative financial group, similar to US Credit Unions. Bank of America ATM holders - use the ScotiaBank ATM machines -- there is no fee involved. One thing to keep in mind - if your ATM pin code is over 4 digits, it may be rejected -- in which case, try only the first four digits of your PIN code, that usually works.
In any case, the spread between the buy and sell prices for CDN$ is pretty narrow - so even in the worst case you lose just 2-3 cents per dollar, so exchange cash (comparison shop before settling on a place), or use a credit card (all of which now charge 2-4% as fees), if that is more convenient than using ATM cards.