Well, it looks like my system is not up to doing much with hair in the Cycles renderer. When I try to render my latest eyebrow attempts, the face disappears. A very disappointing turn of events, that. I was really looking forward to fooling around with the hair editing tools and getting some amateurish but at least interesting results.
I may be able to get something with the Blender Internal engine, but the whole lighting and material system is so much more fiddly and the results so unrealistic, it's really putting me off the whole exercise.