A couple of my friends are visiting Paris from Thursday to Wednesday. Will the best option for them to travel around be using a Navigo Weekly Pass (for two weeks, around 35 euros/week)? We'll need it to cover zone 1-5 (Including from CDG Airport).
Also, can this be obtained at CDG , on a physical card with a photograph, since I am not sure about the compatibility of their phones?
Yes two Navigo week passes (one for Thur - Sun, one for Monday - Wed) will still be their best option. It is still cheaper (60€ + 5€ for card) than the next closest alternative of Paris Visite 5-day, 5-zone + something for another 2 days with coverage for CDG airport, which is close to 95€.
Yes, Navigo cards can be purchased at CDG airport train stations (either at CDG T2 or CDG T1/T3). I would recommend you print your own color face photographs (3cm tall x 2.5cm wide) to use on the paper ID card that comes with Navigo Decouverte card. Doing this prior to departure is easier than tracking down photo machines at the airport and waiting in line and ensuring you have coins, etc.