Hi Guys we have only been to Italy once

There is now an express train between Milan and Zurich. Milan to Como or Guarda are quick and easy train rides. 

For all the places you wish to visit, I would rent a car. That way you can explore little gems along the way. Going through the Gottard tunnel you can explore Lake Maggiore and Lake Como. I would ditch the car while in Milan, though, as it's super congested and the subway system is great. You can re-rent it when you go to Garda. Or perhaps make Milan your last stop before heading back to Zurich! You could take the express train from Milan to Zurich at that point. If you need any recommendations for Lake Maggiore or Milan, let me know!sounds like a great trip!