Initially Duncan is the king in Macbeth, however Macbeth later kills him and becomes king himself.
The speaker in the excerpt is Neptune. Neptune, in Roman mythology (although Greeks sometimes used their names too), is Poseidon in Greek mythology. He is the god of the seas, and he was one of the gods who was against Odysseus and wanted to destroy him - this is why it took Ulysses/Odysseus so long to come back home to Ithaca. The tone demonstrates anger at seeing Ulysses reach Ithaca safely. As I said, he wanted Ulysses dead, which is why he wasn't happy when he finally got home against his will.
It's personification because it's giving human attributes to the storm, which isn't human.
Is slowed by meanders, or curves in the river.
