There is a huge amount of information on the Seat61 website. Whether there are links to individual station maps, I do not know. With a bit of patience you can find them by Googling.
To get you started:
Milano Centrale
Venezia Santa Lucia
Definitely for Paris and possibly for others on your list, the city has multiple "main" stations in the sense that more than one station is used for major international trains. So you'll need to start by going to the Deutsche Bahn website and looking up the schedule for your trips in and out of Paris to see which station(s) you'll be using.
Don't forget that most if not all of your trips will require seat reservations. They will cost you extra. And for trips within France, the number of seats available for pass holders on each train is limited. You cannot necessarily wait until the last minute and get a seat on the train. Of course, trains also occasionally sell out even in countries where there are no quotas for pass holders. I don't know whether you will run into quotas in any of your other countries.
Are you sure that rail pass is going to save you money? You are covering vast distances, so it may, but I wonder. Ticket prices you see online (trainline.eu is a good information source) already include the seat-reservation fee.
If you're looking for street maps, Google Maps are a good start. You can usually get a free or low-cost map from the tourist office in each city. There may or may not be one of those near the train station. This is where you need a good guide book. I think Rick's Best of Europe covers most of your destinations, though quite possibly not Malmo. Among many, many other things, he will tell you where you can find a tourist office. If you can make it to your hotel, you'll virtually always be able to get a free map there.
Incidentally, there's no one on this forum who would suggest that you go to Switzerland and see only Zurich, or to two places in Italy and make one of them Milan. Not unless you're traveling on business or have a family connection. In addition, your itinerary is quite heavily weighted toward high-cost destinations--in case that matters to you.