Angels are depicted in human form because they often appeared as human beings in biblical accounts and because man is like the angels having intelligence and free will. We were created a little less than the angels. Angels have no bodies, so imaging them in human form makes them visible in our imagination and conceivable to our minds.
Angels in the Bible are always given masculine names. Why? Because God is always characterized in the masculine who created the universe from outside himself like a man comes from without to impregnates a woman. Angels are closest to God in nature, therefore, it is fitting to characterize them in the masculine.
Most of the times artists paint angels with wings. They remind us of the swiftness of birds. Angels indeed travel with the speed of thought and wings also remind us that angels are messengers of God.
The painting at the left was done by Raphael Sanzio as the altar piece for the church of San Sisto, Piacenza in c. 1512. The two cherubs are looking somewhere or contemplating. This is first time cherubims are depicted as young children. He was probably influenced by the Roman god Cupid (Eros), the god of love. Most likely Raphael associated Mary with Cherubs to indicate Mary as the beloved of God and to indicate her innocence since she was born without Original Sin.
Ezekiel vision of a cherubim included wings thus: "The sound of the wings of the cherubim could be heard as far as the outer court; it was like the voice of God Almighty speaking." (Ez 10:5) The vision is a composite of images as you see indicating that he was trying to express the vision in the best way he could in human terms. Even artists today combine these images in different ways according to each artist understanding. Ezekiel was not trying to tell us that angels literally have wings.
Usually angels are depicted with a halo, an image most likely derived from the sun which energizes all living things on earth.
Now, an angels has no head as such but consciousness at the center of its substantial form. This consciousness involves intelligence, will, knowledge, wisdom and holiness. An angel stands always in God's presence and partakes of God's glory. Ultimately, the halo symbolizes the life giving energies of God manifested by angels.
When angel's dress is mentioned in the bible they are dress in white, white as snow, with dazzling garments or dressed in linen which was white. Why?
White, as we know, is the reflection of all the colors of light and as such comes closest to suggesting light. "White is associated with light, goodness, innocence, purity and virginity. It is considered the color of perfection." (Website: Color Wheel Pro) In many ways, angels reflect the perfection and glory of God.