Toronto: Airport to downtown. Driving in Toronto is a zoo. Take the train. New and clean.
Fares have just dropped to increase demand. https://www.upexpress.com
Take a taxi from Union Station to hotel. OR The Royal York Hotel is very close.
Use the subway around the city : ttc.ca . They have day passes.
The train from downtown Toronto to downtown Montreal is an efficient choice.
Unusual choice of accommodation, plain, but usually enjoyed by all:
https://www.saint-joseph.org/en/visit-us/lodging
Montreal to Quebec City and back: Rent a car. It's just easier and in my experience is much cheaper. unless you can arrange for a cheap drop charge in Ottawa. YUL-YOW is 200 km.
Quebec City is a jewel. Just for the historic atmosphere. Allow a disproportionate amount of extra time there. You will remember it. More than any of the other places!
Ottawa...no more than 1 day IMHO.