Paris Nord to CDG

If the pass is good from CDG to Gare du Nord, then it's probably also good from Gare du Nord to CDG. However, unless you have pass days to waste, just buy regular tickets. The fare from CDG to anywhere in central Paris on the RER and Metro is €9.50.

We will be arriving in Paris by rail so we would not be using an additional day on our rail pass. I will check at Paris Nord to see if a voucher is available, if not I will plan to have the euros needed for the fare.

The actual name is Contremarque de Passage. You need one because in order to use the gates you have to put a ticket in to open the gates, and when you leave the system you need to put your same ticket in to open the exit gates. Not so easy when you are using a pass. First, you need a human operated gate because you large rail pass won't fit into the half inch wide ticket reader to open an automatic gate. So you need to find a window next to the ticket line. Next, that window actually has to have a person behind it. Voice of experience here. As they accept your pass and open the gate for you to go through make sure to ask, "Un Contremarque de Passage, svp". They then hand you what looks like a Métro ticket but isn't. Go through the gate and save that piece of card. When you are at your destination put the card into the the reader and wait for the clunk that says that it is open and push through. If you don't have one you will be like Charlie on the MTA. I have never seen an attended exit gate. Note that the pass is ONLY valid on those short parts of the RER noted. They are operated by SNCF. All the other parts of the RER, and all of the Métro, are operated by RATP and passes are not valid. If inspected on RATP lines using a pass expect a very large on the spot fine.