Does Sessions have control over my Calendar?
No, Sessions can't control your Calendar. User emails integrated with a calendar (Gmail, Outlook, Apple Mail, and others) will analyze the emails sent by Sessions. If an iCalendar attachment is present, it will create a pending event and notify you about it (if this is the default setting). When you are invited to a session, you can decline or accept the invitation. However, as the creator of that session, you are accepted by default.