Yes. It is the French term for "policeman."
A gendarme is a policeman or constable. A gendarmerie is a police station.
No, a gendarme is a French policeman.
Les gendarmes are the police.
A gendarme is a military man with the same power of a policeman.
French is "français" (feminine: française; plurals: français/ françaises). Here the word français is an adjective, so use a lower-case f. A Frenchman is 'un français', a Frenchwoman is 'une...