DexyMan: I'm not sure if you mean the casts of his stage productions or of his radio productions, or both.
This Is Orson Welles, the book of interviews between Welles and Peter Bogdanovich, contains in its revised edition (by Jonathan Rosenbaum) several useful appendices, one of which covers, in timeline fashion, what you seem to want.
Without dealing in the individual books, I would say that it would be difficult to understand fully in any respect Welles' career without knowing the shaping influence Radio had on his work. In my judgment, his early achievements in the Movies were largely so striking because he understood what could be done with sound: the creation of sound stages. [The RKO Sound Department was ecstatic to have the cooperation at last of someone who understood what might be accomplished with microphone placement, sound levels, the almost poetic blending of dialogue and music.] Ironically, his later work appears to have been crippled because he did not have the equipment or the technicians to make use of many sound techniques he had introduced into Hollywood.