The finished product formulator is highly dependent on the BPC manufacturer to provide bulk substances uniform in chemical and physical characteristics.
The improvement of the purity of fluorene is not dependent on the removal of acenaphthene and dibenzofuran, but dependent on the separation of other impurities.
Research choices are often dependent on the specific civ, but you are going to want to get Iron Working and The Wheel sooner rather than later, just so you know where the iron and horses are.