No.
Yes, Magnum reveals it all in the last episode when he dies.
Higgins is definitely not Robin Masters on Magnum PI. Too much evidence in the episodes indicates that Higgins is just Higgins. Robin Masters is present, though not clearly shown, in at least a few episodes. You can't know that, it was deliberately left open to interpretation. Yes he is. Magnum says so in the last episode when he dies.
Nope. They never show who Robin Masters is, although it is believed to be Higgins. There is never an identity to Robin Masters.
Magnum reunites with his daughter Lily; we do not learn whether Higgins is really Robin Masters; TC reunites with his family, and it is left open whether Rick marries Chloe.
Its not really Magnum's house. He just stays there. It is owned by Robin Masters
Robin Masters
No, Robin Masters owned the Ferrari
Yes, Magnum reveals it all in the last episode when he dies.
True
Magnum's PI license plate, "ROBIN-1," refers to Robin Masters, the fictitious author and owner of the Hawaiian estate where Thomas Magnum lives and works as a private investigator. The name signifies Magnum's close association with Masters, as he often drives the Ferrari 308 GTS belonging to him. The "1" in the plate indicates that it is the first vehicle associated with Robin Masters, emphasizing Magnum's unique role in the story. This clever choice adds depth to the character dynamics and the show's setting.
Magnum PI
Robin Masters, the novelist, on Magnum P.I.