A.2.: Possessions remaining loyal to Vichy in many cases could only use Third Republic Issues, examples easier to find and identify for those colonies. Adherence to Vichy France:
November 1940: Gabon
July 1941: Syria, Lebanon
December 1941 St. Pierre and Miquelon
May 1942: Wallis and Futurna Islands
November 1942: Algeria*, Dahomey*, Togo*, Madagascar, Ivory Coast*, French Guinea*, Morocco*, French Sudan*, Senegal*, Tunisia*, Gabon, Reunion
(* but not fully Free French for another year).
Left: Algeria, posted 10/25/40 from Miliana, Algeria to U.S., paying 2 fr. 50 centimes rate for surface transport. The 90 c ship stamps date to 1939 just before the defeat of the French Army.
Right: French Guiana switches to Free French on March 16, 1943. Mailed on 4/6/42, the cover arrived in NY on 4/18/46, taking the extraordinarily circuitous route shown in the upper left corner: