1)
How did Hashem tell this to Yehoshua?
1.
Radak: Hashem spoke via the angel.
2.
Malbim: Hashem told him directly.
2)
To whom does "Giborei ha'Chayil" refer?
1.
Radak: The people of Yericho and their king. Even though they are mighty, I give (conquest of) them to you. Malbim
