1)
What is the meaning of "Peh Echad"?
1.
Radak: It was one agreement and counsel. Targum Yonasan is like this.
2)
Why did the nations gather?
1.
Radak: It was due to the episode with the Giv'onim. (It is written out of order.)
2.
Malbim: Refer to 9:1:1:2.