We have a connecting flight in Paris with a 90 minute layover before we board the next plane to Athens. Do we have to go through passport control and customs before boarding the next flight? We are flying Delta from the USA and switching to Air France (their partner airline). Will we have to change terminals? Is this going to be an impossible feat?
Should work if everything is running smoothly. If there is a delay, it will be Delta/Air France's responsibility to put you on their next available flight connection. You might want to check on when that flight is. In cases like this, you are often switching form Terminal 2E to 2F, which I did not find to be as close as they sound, since CDG is huge. You will go through passport control, and timing varies. In one of my trips, passport control took 45 minutes making me and other customers miss our connection, but there was another flight available in a couple of hours. There is an assistance desk for this type of issue.
I would think 90 minutes would be the minimum connection I would want in Paris. Longer would be better if you want to use the facilities. We were in long lines that were not very well managed (backed up way down a long hall, and you couldn't tell where you were supposed to be until you walked to the length of the hall to read the line signs, so wasted a bit of time there) and though we did make our flight, we were near the last to board and we had an 80 minute layover. Once a few years back going to Cairo, we had to walk many halls until we got to a door to take a BUS to our terminal. That was a long layover and we needed every minute. Glad we didn't experience that this time.
If you have checked bags, make sure Delta puts special "short connection" tags on the bags when you check in in the USA. Also make sure you get your boarding passes for the Athens flight then too. Take what you need for the first 24 hours (48 even better) in your carry-on. If you are checking 2 bags, don't do his and hers - mix them up so if one goes astray, you both have things until the lost bag catches up with you.
Get seats near the front of the plane for a faster exit. Tell the flight attendants that you have a short connection. Once you are in the terminal, if you have to wait in line, tell the staff that you have a short connection. They'll often expedite your passage.
Check your tickets - they usually include the arrival and departure terminals for each flight.
Lastly, use the toilet on the plane before you get off.