"I am very confused now. I booked the train tickets from tgv-europe.com/en and that is the itinerary (departs 12h36, route CDG-Strasbourg-Basel-Zurich). Now the German website shows different depart time (12h40) and route (CDG-Gare de Lyon-Zurich). Which is my actual itinerary? Also, what do I need to do about "reservation" to any of those legs?" Relax Mau, there are usually multiple different routes to get the the major destinations in Europe, your chosen route is fine and at least it does not involve a switch of stations in Paris!!! As regards reservations, here is what I find: 12:36 Aéroport Charles-de-Gaulle TGV to Strasbourg Ville - Reservation required, and you have it 15:51 Strasbourg Ville to Basel - A Regional Express, so reservation not possible, just grab some free seats.
17:33 Basel to Zurich - An Intercity, no reservations required nor available on line On the trains where you have no reservation, you simply look for some free seats, if there is someone else already there just ask if the other seats are free and if so, sit yourself down. The train you are taking from Basel to Zurich will be at the beginning of the rush hour, so you may find that it is rather full. If so, not to worry as there are plenty other trains heading for Zurich and your ticket is good on all of them. Other departures to Zurich are at: 17:36, 17:47, 18:07 and 18:13. Depending on how you are feeling by the time you get to Basel, it might even be an idea to have a little break, get a coffee and take a later, much less crowded, train down to Zurich.