Why does it say that the animals will not fear?
Radak: Above (1:20), it said "Gam Bahamos Sadeh Ta'arog Elecha." Sadai is like Sadeh.
Malbim: Had the salvation been for His great name, He would have returned the grain only in settled areas, but not in the Midbar. Rather, it was in the merit of Yisrael, therefore also the Midbar sprouted grass.
Why does it say "Ki Dash'u Ne'os Midbar"?
Radak: Above (1:20), it said "v'Esh Achlah Ne'os Midbar." Since they became full of grass, so the streams became full of water.
Malbim: Refer to 2:22:1:2.
What is the significance of trees bearing fruits?
Radak: Just like trees bear fruits in settled areas, so grassy areas in the Midbar will sprout grass.
Malbim: This was a miracle. There was a general salvation in all places and in all species.
What is "Cheilam"?
Radak, Targum Yonasan: Their strength, i.e. their fruits.