I agree that Jill would have been a good choice, but, and I base it solely on the cast recording, Lauren Ward is quite stunning and I really do hope that all the evidence pointing to her doing it here turns out to be correct.
I don't know how the rumor mill is shaping up for the casting of Mrs. Wormwood, but I was monitoring another audition a few weeks back and heard Nikka Graff Lanzarone's audition from the hallway and I think she would be phenomenal in the role.