Last year we saw Rent in Phoenix in March and in Dallas in May (with Anthony Rapp and Adam Pascal.) During that time, a couple of cast members in the touring company had changed - who knows what happened...
If an actor wants to take over a touring role that they've done in the Broadway production, they usually get first dibs as they already know the choreography & staging. It's usually the same, with subtle adjustments for each theatre. This way, any cast changes are seamless.
The per diem for doing a tour is excellent. If the cast member saves most of the per diem, instead of lavishly wasting it on expensive food and frivolous stuff on the road, the per diem alone is worth going on tour for.
Not true. Tours are usually only in a city for a few days. It would be completely impractical and hard to reteach the same numbers over and over again in each city to new people.
I think she was talking about "extra" type roles. Not fill-ins for speaking or dancing roles. Like if
My fair Lady, needed lots of people for a particular ballroom scene or as patrons in the horse race scene, the show might get locals to fill in the extreme background, in costumes provided by the costumer, the local theatres or those extras, if they have something that works. They would just sit or stand in the background. No extreme choreography or staging. It would be impractical to travel with a large cast that they don't need as understudies or for regular chorus roles.
The locals get a kick out of it, as they remember the event.
Also, sometimes, this is the only real interaction the cast gets with the audience in each city. My friend, who toured
Mamma Mia, said they loved when there were meet & greets after the shows, when certain groups got to stay and ask the cast questions afterwards. Otherwise, it's travel, do the show, go to the motel, hop on the bus to the next city.