With your BA Gold status and your France residency, you should be able to get a status match from BMI which will grant you *G status immediately. The BD network isn't that great, but with gold level, you'll get 25% bonus on any *A flight, as well as a very generous cash+miles redemption program. You are also entitled to a "soft landing" if you don't maintain your gold status, meaning you drop down to silver before you plunk to basic blue. The BD *S status would still give you the 25% bonus on any *A flights, as well as access to select BD and partner lounges. The BD membership year runs from the time your membership becomes active.

More details are in the BD forum, especially on Wingnut's very helpful sticky.

Yes, good luck with the move!