Arriving at CDG on a Sunday afternoon. In Paris, Monday, Tuesday, then Disney on Wednesday. Flying out of Orly on Thursday. Advice on the best passes for our stay with kids please. Thank you!
I'd recommend Navigo Decouverte pass for each of you (kids included, no discount for them, but still the cheapest option). Even though you won't be able to use Navigo on Sunday. Starting Monday the Navigo pass will cover you inside Paris, out to Disneyland, and Orly by Orlybus from Denfert-Rochereau bus station (or Tram 7 from Villejuif Louis Aragon station on Metro line 7). Do not use OrlyVal train to get to Orly. It is not included in Navigo.
For arrival and getting into Paris from CDG on Sunday I'd get single-use RER tickets.
You can buy all tickets/passes at CDG Airport when you arrive. Either CDG Terminal 1/3 train station or CDG Terminal 2 train station. After that you won't need to line up to buy any tickets.