We were just there last summer. You can buy a Parks Canada pass at any of the entrances to Canadian Parks. We got ours at the entrance to Banff. I don't know how much this year's pass will cost.
We got Canadian cash at our local bank before leaving home. Frankly, there were some places that I didn't feel comfortable using the credit card (in the US as well), so the local cash was used. Further, make sure you have some $1.00 and $2.00 Canadian coins on your person. Some CGs that charge for showers/laundry will necessitate the use of these coins.
Agree with the purchase of our tour saver book.
Best wishes for a great trip.