Google Groups can be used as an efficient way to manage permissions for many members at a time.
Google Help: https://support.google.com/a/answer/167101?hl=en
Google Calendar
When you share a calendar with a group (simply use the group's email address), all members of the group (and its child groups) will be able to access the calendar.
Google Drive
When you add a group to a shared drive, all members of the group (and its child groups) will have the permissions assigned to the group.You can also share single files with groups, just as you would with a single person.