So will Cycles automatically convert Firefly materials or settings, or will you have to manually adjust in order to use in Cycles? Say for example I have a character with skin. How will that skin look in cycles? What additional work if any will have to be done? Or will this bridge do most of the work for you? Or will there be convert presets available eg an ezskin type product for cycles?

Most, but not everything. Some stuff just doesn't translate to a physical render. Gather ... what's a gather node going to do in a physical render. That's what a physical DOES. Also part of the idea of the physical render is to reduce the need for some complexity in the shaders. We should be able to eliminate or at least reduce the part of the shader devoted to the way light responds to the material. That will be the render engine's job now.