What is "va'Yeromu"?
Radak: It is an expression of elevation. In the first vision, it was called Nesi'us; it is the same.
Malbim: They were not going to another place, only to be elevated above the ground, i.e. to conduct according to Hashgachah. This is depicted as flying (refer to 10:15:2:2).
Why were they called Chayos above, and here, Keruvim?
Refer to 10:9:1:1*.
Malbim (9): First he saw how the Chayos conduct the Ofanim according to the Ma'arachah and nature - this is during Galus. They go [with their feet], and do not fly. Therefore they are called Chayos, which go with feet. Now he saw conduct outside of the Ma'arachah - burning the Mikdash and saving Yisrael. Flying hints to this - they fly above the land and the natural order. They are called Keruvim - their wings, for flying, are primary. They receive this influence from Kisei ha'Kavod above, therefore first he saw the Kisei, which is primary in this conduct.
