Is there a word to describe or reference feathers, scales, fur, hair, exoskeleton (maybe?), etc. on a creature?
It is called an integument.
integument, in biology, network of features that forms the covering of an organism.
Among unicellular organisms, such as bacteria and protozoans, the integument corresponds to the cell membrane and any secreted coating that the organism produces. In most invertebrate animals a layer (or layers) of surface (epithelial) cells—often with additional secreted coatings—constitutes the integument. Among the vertebrates the boundary covering—with a variety of derived elements such as scales, feathers, and hair—has assumed the complexity of an organ system, the integumentary system.
It can be called integumentary system or body covering also. Here is a detailed list of integuments from the University of British Columbia, Department of Zoology: