The image of God is to be understood in spiritual terms, not in physical terms. God is spirit. Man also has a spiritual component, and angels are only spirit (though, angels are not all-powerful spirits as God is). The image of God means that one has the same potential as God, that one is truly a son of God; of course, each according to his measure. The characteristics of this image are that one is a person, as God is Personal, and all the characteristics of a person: that one has free-will, rationality, responsibility, love, humility, etc.
Angels are most definitely made in the image of God. To say otherwise would place them in a category similar to animals. What angels do not have is bodies; thus, they are different than humans, but not that different as to not be real persons with real will-power.
The likeness of God has to do with how much creatures resemble God. Both man and angels are supposed to become like God through the process of theosis, which is infinite. So, the image of God is given by Him, but the likeness also depends upon the will of the creature, in addition to God's Grace that helps us become more and more like Him.