13 days there and back is not my definition of "taking your time"
That's 10 places in 13 days! You could spend several days in Toronto, Montréal and Québec easily.
Saguenay is the name of the river and its fjord when it reaches the St-Laurent river. Tadoussac is the name of a beautiful village where the fjord is located. It's a good place to walk along the river, book a wahles watching cruise, etc. Be warned that to cross the fjord to reach Tadoussac when coming from Quebec/La Malbaie, you have to take a ferry and the wait can be long.
In Quebec, there is a LOT to see. The Old Town is wonderful to spend a day exploring, the port also, there are superb restaurants, you can go to the island of Orleans for a more rural feel (the wineries, cider houses, chocolate stores are wonderful, plus a few restaurants open temporary sports there. Look for Panache Mobile, a sure bet). The Montmorency waterfalls are also worth a visit. There are a few museums, one of Arts located near a large park, one covering modern topics in the old Town. the Bois de Coulonge is another superb park. You can visit the Promenade de Champlain, a beautiful boardwalk along the St-Laurent. There are excellent shopping centers if you're into that sort of things. The city Observatory on the top of our tallest building is also nice, you can also visit the parliament, etc. You can take the bridges or ferry across the river and see a beautiful sunset over the Old Town from there. There's really a lot to do.
The same could be said of Montréal, which does not have the beauty of Quebec, but has a more dynamic nightlife, great restaurants, several museums, a lot to see and to do. The same can be said of Toronto.
Wendake is in a suburb of Quebec city, it's interesting but don't plan on spending too long there.
La Malbaie is another nice village, but Baie St-Paul is close and more beautiful. There's a huge and impressive hotel/castle/casino at La Malbaie however.
Belleville and Lac Taureau, I have no opinion.
I hope I answered some of your questions!