1)
What is the meaning of "umi'Yam"?
1.
Radak: These are those who go on the sea from land to land. Hashem will return them.
2.
Malbim: It is from islands in the sea.
2)
Why does it mention all directions except for the south?
1.
Radak: It is least settled of all directions, due to heat of the sun. Few people go there for business.
2.
Malbim: There is no settlement in the south.