Hello Peter,
Some answers to your questions:
1- Frigate depicted on the box is La Découverte (ex- HMS Windrush) one of six such River frigates in service with the Free French Navy during WWII.

2) You can build any of the class with the decals provided, pennant numbers starting with K, you have enough in the box.

3) What I usually do to display full hull models, is to drill two small hole on the bottom hull, insert a piece of brass rod in each, and place the model on a piece of vanished wood (usually cherry tree wood that gives a nice color)
Hope this helps,
Best regards from Normandie,
Jacques Druel