Icons are much like gods. They can be very powerful and are sustained by belief. However, their connections to belief are very different. A God is sustained by belief in their reality, whereas Icons are born of and sustained by belief in an ideal, personified in some symbol.
As an example, Uncle Sam is an Icon. He personifies belief in the American Dream or the American Ideals. As such he has a very strong connection to the USA and has a kind of omniscience in its borders. If he knows who or what he is looking for he can instantly know where it is as long as it within the borders of the USA.
Also, unlike a god, an Icon does not have to answer to prayers, but as a representation of ideals it is severely constrained by them. Sometimes those ideals may even come into conflict. An icon could represent the ideals of equality, but also the ideal of the sovereignty of the government. If the government is being discriminatory, this Icon could have a lot of trouble resolving the issue.
If you decide to be an Icon, your High Concept must have some implication of the ideals you represent.