If you've haven't read "This Is Orson Welles", the big book of interviews between Peter Bogdanovich and Orson Welles, you should. It's as important as "Hitchcock/Truffaut" and it may be argued that there's more practical knowledge to be found there. Welles was as much a self mythologizer as Hitchcock but he switched out his material more often.
Most of the interviews conducted for the book and, if my memory serves me, some that are not in the book are to be heard here in the tapes Bogdanovich made for the book.
Welles' words are interesting and valuable on the page but when you hear that voice it gives a whole additional dimension to the stories.