1)
What is "Shleiv"?
1.
Radak: It is [serene,] like "Shalev Hayisi" (Iyov 16:12), just here there is a Sheva under the Shin, like She'er, Pe'er and Ze'ir.
2)
Why does it mention that the nation is serene?
1.
Malbim: You will not need to search where they are. They do not think to flee!
3)
What is the meaning of "Badad Yishkonu"?
1.
Rashi: They are confident alone. They do not need to gather and dwell among many people, for they do not fear lest an enemy come upon them.
2.
Malbim: You need not fear lest their neighbors help them, for they dwell alone.