I saw that the options are there for SMS and email communication - I assume that this can be used for all - parents, teachers, and students?

It can be used via role, course, class, year group, form group, activity, and a range of other target types that Gibbon is aware of. Really saves time syncing your email mailing lists! SMS requires credits on an external gateway so we generally use it for emergencies only, but that will depend on your budget.