Appointments+ Canceling and Rescheduling

Questions about rescheduling and canceling appointments in Appointments+.

1) Where do I find settings to create and manage the rescheduling process? How do my clients get an rescheduling link?

2) If I cancel a time slot that already has booked clients, is there a way to message all of these clients automatically? If so, is there an interface to manage this process?

Thanks