Structure-Property Relationships for β- and κ-Phase BEDT-TTF Salts and their use in the Synthesis of κ-(BEDT-TTF)2Cu[N(CN)2]Br: A Salt Having the Highest-TC (Inductive Onset = 11.6 K, Resistive Onset = 12.5 K) Yet Observed in an Organic Superconductor