Such descriptions are either literary devices, or symbolic revelations meant specifically to the seer's awareness that communicate a deeper reality regarding their nature. The meaning of these symbolic manifestations must be found in the collective "exegesis" of these symbols in ancient Israel, and in the greater cultural and religious context of the ancient Middle East at the time the revelation was granted.
Angels, being spiritual beings, don't need eyes, heads, or multiple faces. These are symbolic of the speed and depth of angelic perception, as well as their speed (when it comes to "wings".
God is also described in Scripture as having a "back", as well as "wings" and "pinions." He does not, but these literary artifacts are descriptive of aspects of God's reality who, in His Being, has not and needs not any of these appendages.
+JMJ,
Theo