In what sense are sin and evil different realities?

Sin and evil, in realities, are different in the sense that sin is not freely chosen, rather, an act that is regarded as a transgression of God's will. Sin, however, is that which causes harm, destruction or misfortune to all God's creation.

What are a few ways that the Jews had already seen God's kingship?

A few ways that the Jews had already seen God's kingship was in the "wonders of creation" and in the Torah.