Assemblies and methods to enhance hydrotreating and fluid catalytic cracking (FCC) processes associated with a refining operation, during the processes, may include supplying a hydrocarbon feedstock to a cat feed hydrotreater (CFH) processing unit to produce CFH unit materials. The assemblies and methods also may include conditioning material samples, and analyzing the samples via one or more spectroscopic analyzers. The assemblies and methods further may include prescriptively controlling, via one or more FCC process controllers, based at least in part on the material properties, a FCC processing assembly, so that the prescriptively controlling results in causing the processes to produce CFH materials, intermediate materials, the unit materials, and/or the downstream materials having properties within selected ranges of target properties, thereby to cause the processes to achieve material outputs that more accurately and responsively converge on one or more of the target properties.