If you have an overnight stay at CDG, you *can* ask to have your bag checked through all the way.

However, given my experiences of luggage always failing to make the connection at CDG - even when deliberately choosing longer-than-necessary layovers in order to allow more time for the bag to make it - I now actively avoid CDG as a transfer point. If I were you, I would instead ask to have my bag checked only as far as CDG, retrieve it and take it with me for the night, and check it in again the next day for the next flight.

(While I accept that many people will have gone through CDG many times with no baggage issues, I genuinely am not joking when I say that every time I have transferred at CDG, my bag has never arrived on the same day as I did at my final destination. I, clearly, am jinxed).

If you do have it checked through, I would approach the gate agent the following day, ahead of boarding, showing your luggage receipt and asking them to ensure that your bag has been loaded. Also, don't just let them fob you off with assurances - insist that they check in the computer.

Foie gras will be confiscated from you at security at CDG (unless you were somehow able to source portions that meet the standard liquids-on-board guidelines!) and as such would have to be checked in with your checked luggage rather than carried on board. Three hours is not enough time for you to leave the airport, though. As suggested above, you can purchase foie gras while airside at CDG itself - this is the only way you would be allowed to board with foie gras (keep it in the sealed clear plastic bag until you arrive at your final destination).