4) It would be better to show the answer "Congo Free State", though it is indeed the same territory as Belgian Congo then Zaire, then DRC.
7) Saxophone, ok, that has already been said.
14) Nothing wrong, but Tintin would be more representative than the Smurfs (because Tintin is a Belgian guy, and his adventures are snapshots of Belgian and World history, especially in the 30s).
15) On the other hand, Poirot has nothing to do here. It's British literature, not Belgian history.
17) Battle of the Bulge