Think of Firefly as being a loving but over protective parent, moving to another render engine is like one's first day of school, some re-calibration of reality is required. Recommend focusing on the lighting first. Use a simple sky dome + one infinite or area light, Snarly's ezdome is ideal for this. For materials the physical root node is a lot simpler to use than the cycles one (also more accurate) so the better one to start with, don't need to understand PBR just don't change the specular value. Once happy with the lighting, experimenting and using the cycles nodes should be more straight forward. Smith Micro have a video on their Youtube channel where they discuss using Physical root node but also includes some info on the problems of using FF mats in superfly.