What do we learn from "Choveres Ishah El Achosah Kanfeihem"?
Rashi: The wing of this one is spread to the side of the wing of this one here, and also on the other side, until they touch and join one to another, and so they cover the faces; the wings extended above the faces.
Radak: Ishah El Achosah means one to another, like it says about the curtains of the Mishkan and the Keruvim (Shemos 26:3, 25:20). 'Ish' and 'Ishah' apply to anything (not only to people).
Malbim: The verse teaches about the pairs of wings [touching each other] to teach that that do not have unity like their Creator. In any case, they are connected. They are pure intellectual, non-physical beings. Their understanding is sudden; there is no separation of time of place.
Why does it say "Lo Yisabu v'Lechtan"?
Rashi: If they want to go in a certain direction, they need not turn their faces, for they have a face in every direction. They go as they want, and there is a face facing that way 1 .
Malbim: Because they have wings in every direction, they need not turn their faces when flying, for they fly with the two wings in the direction in which they need to go.
What happens if they want to go on a diagonal, e.g. the faces face north, east, south and west, and they want to go northeast? Perhaps they go north, and then east, and reach the desired place, but not via the shortest path. (PF)