I know I want 5 Navigo Découverte Cartes with "Forfait Semaine Toutes Zones". I will have my photos, pen, and credit card with chip. Do the "Tickets et Navigo" machines at CDG train station sell Navigo Découverte Cartes? Or must I go to an SNCF agent at the counter to buy these?
The ticket vending machines and Navigo recharge stations do not sell the physical Navigo card itself (no vending machines do). You'll need to visit a ticket window / ticket office to buy the Navigo Decouverte card from a human agent (and they can also put the week pass subscription on for you at the same time).