What are the Pesilim?
Rashi, and Targum Yonasan: It is where they quarry rocks from the mountain.
Why did he leave and return? He could have killed him the first time. He knew that when he says that he has a secret, Eglon will expel everyone!
Radak, Malbim (18): (a) It was to make it seem that he came primarily to bring the gift. It seemed that he forgot that he also has a secret to tell, and returned for it. (b) If they will realize [that he killed the king], it will be easier for him to flee [alone], than if he was with the others who brought the gift. Malbim - now, they will not be in danger.
What is the meaning of "Has"?
Rashi: Eglon said that everyone should be quiet (Radak - until everyone leaves).
Rashi citing Targum Yonasan: He removed everyone. Yonason agrees that it is an expression of silencing, like "va'Yahas Kalev" (Bamidbar 13:30). Expelling everyone is the ultimate silencing!
Where was Eglon?