I'm not sure what you're asking, but the first itinerary does NOT consist of all DL flights. The DL 9XXX nonstop YYZ-AMS is really KLM while DL 8XXX nonstop CDG-YYZ is really an AF flight. These are codeshare flights as DL does not serve these routes. Note also that your 3XXX transborder flights in both directions will be RJs operated by some DL connection carrier, although they could still depart from the traditional Canadian gates at MSP around G8, the ones with the narrow but very deep gatehouse.

Several years ago, a friend of mine flew from MSP to AMS via YYZ and thought it was a miserable experience. Apparently he was kept in some horrible transit holding pen area of the airport and did not have access to lounges, airport shops, F&B outlets, etc. I suspect that there was also a bus transfer between terminals.

On the return, AFAIK you would first enter Canada to go with your luggage to the transborder customs and immigration processing area; I don't think there's a way to get into the line without mingling with the passengers who are departing from Canada but I've never tried this myself. Upon arrival into the USA, this would be treated as a domestic flight.

The schedules look pretty good to me, so if you're not normal lounge users, I'd be inclined to save the $300 each for four passengers.

Have you tried to look at the YYZ airport website for information? What do KLM and AF say on their websites about their gate locations and facilities at YYZ?