1)
When did they want to dispossess [the residents of these cities]?
1.
Malbim: It was after Yehoshua told them [that they may dispossess them and take the cities] "v'Hayah Lecha Totz'osav" (verse 18).
2)
What is the meaning of "va'Yo'el"?
1.
Rashi: They desired.