1)
What do we learn from "Kasher Tzivah Hashem Es Moshe Avdo Ken Tzivah Moshe Es Yehoshua"?
1.
Malbim: Moshe passed his tradition over to Yehoshua (Avos 1:1). Also, even though had Moshe [entered the land and] conquered, it would have been more miraculous, Yehoshua did not deviate regarding the conquest and division.
2)
Why does it add "Lo Hesir Davar"?