Pretty much in agreement, good idea to size, it trues up any dings from shipment if nothing else and makes for uniform cases. Also a chamfer tool isn't necessary, but makes loading .454 lead bullets a lot easier, and makes running the brass into the expander die easier. As does a shot of lube. I like One shot, I hate it for any real serious resizing like bottle necked rifle, but it makes even carbide pistol dies run a lot smoother.
It's not a bad idea to trim new brass, but spot check Starline and unless there quality has went down a lot there's no point with them. A batch of Winchester I got several years ago on the other hand... Also since the rimmed case headspaces on the rim, as long as the case isn't so long it gets into the chamber throat it's not going to hurt anything. They will split long before getting too long.