1)
Why does it mention mountains and hills?
1.
Radak: After mentioning things in the air, and it mentioned them next to water, because due to water vapors rise from which come rain, snow and hail. Afterwards it mentions the dry land and everything in it. Mountains and hills are the land creations that endure. They include all inanimate things, for metals are in them - "Eretz Asher Avaneha Barzel
2)
Why does it mention fruit trees and cedars?
1.
Radak: After mentioning the inanimate, it mentions the vegetative. Cedars include all barren trees; it mentions them, for they are the tallest trees.