Does this register the visitor?
No. There is no RSVP, reminder, or contact created by these buttons.
Did the calendar app save the event?
A new tab, Outlook on the web, or a downloaded .ics file is not confirmation. The visitor still has to finish the save in Google, Yahoo, Apple Calendar, or Outlook.
Does it support repeating events?
No. Each action is one event.
What about Bookings?
A Bookings service id is not an appointment. This release does not add a booking to a calendar.