George,
1. It would be a good point by and large to start your essay with the notion of complexity, its properties, and its definition(s). The thing is that "complexity" in itself is, ahem... complex.
The most important (and you won't find it in any textbook) is that there is no objectively complex things in the nature. All the complexity resides in our brain. There are systems around us comprising various number of elements with different interrelations. Some of them are regarded by us as "complex" - but there is no direct correlation between those numbers and the observed complexity.
2. From this point of view, cognitive psychology and the new discipline of judgment and decision making will be of more help than cybernetics. The only useful thing from the cybernetics field I see is the Ross Asby's law of requisite variety. Managing complexity should not be equal to fighting complexity by reducing it. Managing complexity means harnessing it, balancing the inevitable outside complexity with carefully engineered complexity of your organization.