Dynamic access/membership/assignment

Hi everyone,

Can anyone tell me what happens in the two cases below?

Case 1: I created an assignment for a person who fulfills a certain role. If that same person changes roles, what happens to the assignment? is it cancelled?

Case 2: if I add a person, who holds role X, as a mandatory member of a community: what happens if that person changes role? is she removed from the community?

Can the person who changed roles, who now holds role B, be automatically added/moved to the community whose members were added based on criteria "role = B"?

Thank you

Alessandra