"and the Abarian heroes had treated it in the same way..."
See in text (Chapter III)
By showing that the Abarian heroes have behaved as badly as their Bulgarian counterparts, Voltaire evens the playing field, so to speak, so that neither side can be seen as more or less evil than the other. Rather, it is war itself that is evil, which leads us to Voltaire's implicit question: “How can a benevolent God permit this terrible evil to happen?”
See in text (Chapter IV)
The word "spectre" typically refers to a supernatural apparition or a ghost, but is here used metaphorically to refer to the "spectre" of this beggar, who, as we soon learn, is actually Candide's former teacher, Pangloss, here presented as a ghost of his former self because he no longer commands the same respect as he did.