1)
Why does it say "Al Arba'as Riv'eihen b'Lechatm?"?
1.
Rashi: Before it taught about the Chayos (they can go in the four directions without turning). Now it says that the Ofanim do not impede them, for also they are made to do so.
2.
Malbim: Each day they go from east to west, and act during the four quarters of the day. Every six hours a Ru'ach is aroused from a different direction, like Chazal said (Gitin 31b). Every half year they traverse their path from south to north or from north to south, and the yearly orbit from west to east, and different actions during the four Tekufos - cold and heat in the four directions.
