Ok for the ferry, make sure you buy your tickets on line first. If it is busy, take the ward island ferry. ( they are all attached).
You are going to take the QEW which becomes the Gardener. There is construction there and it will be slow. There will be a sign on the highway which will tell you if Lakeshore is faster. I use a parking app to find the cheapest parking if I have the car. Last year I found cheap parking in the ICe condos which are being built.
To get the the Eaton Centre take Bay st north then merge to the left into University. Turn right onto Queen just past the next light you will see a green parking lot on the left under Nathan Phillip Square. This is the easiest cheapest parking I've found. It's a short walk to the Eaton centre. If it is raining, you can stay under ground by following the directions to the Sheraton which is attached. You can also take a picture with the famous Toronto Sign.
The Shearton is a nice hotel but what I would do is after your shopping evening, I would head north to a hotel so you are not stuck in the morning commute when you are going to Canada's Wonderland. Traffic should be lighter around 10 at night.
There are a series of hotels in Vaughan just off highway 400 and 7. You will find cheaper rooms, free parking and be minutes from Wonderland in the morning. A lot of them have package deals. I've been very lucky with Priceline in this area. ( last summer I was getting $65 rooms) All the hotels in the cluster by IKEA are good. Residence Inn, Hilton Gardens, Courtyard.