This only allows them to see when you are busy, it does not allow them to read your events or to-dos. You should leave this default alone. When inviting other people to events, make sure you give a meaningful title to the event, and a location if necessary. You do not need to list the people who are invited, as they can look at the list of invitees. For lengthy descriptions of location or agendas, use a pop-up note instead of adding it to the event title.
Any invitee can add a pop-up note to an event.
As a group, you should decide whether to rely on responses to event invitations. Response lists are only reliable if everyone in the group habitually responds to events. Synchronize uses color and type style cues to inform you about the status of the users who show up on this list. Choose groups of people in the right-hand box above the list of names. Limit the display based on user status for the event from the left-hand box.