Don't know if this is exactly what you're looking for, but a book that I really enjoyed was Unnaturally Green by Felicia Ricci (an Elphaba stand by for the San Francsico run of wicked in 2010. It's about her journey from auditions to SF's closing night. It's really a book about her, and what the experience was like, but at the same time, there's a lot of bts information on what the audition and rehearsal processes were like, how it all works trying to move across the country, what it's like back stage, all that kind of stuff, and I really loved it. (It's also really funny, because she has a wonderful kind of self deprecating, but very honest humor)