re: Why did Gina Ferrall abruptly leave MAMMA-MIA?
Ferrall's injured. She's actually been out and covered by understudies for most of the summer and they ultimately ended up bringing in Briner (who, as Kev said, played Rosie on tour) to start with the new cast. Briner is supposedly on a six month contract, after which there is a possibility of Ferrall coming back, but whether that will end up happening or not remains to be seen.