I guess you can say that every actor is a 'character actor' on some level. But I think some actors have a wider range. I think that's how you get that mantle.
Bent metal is worse than bent wood and weight for weight is more flexible.
I don't know how it is now but the assistant stage manager had to understudy several parts. You had to be ready to go on at any time if the actor couldn't make it to the play. I didn't think anything of it.

