You can enable and disable comments for event(s) by clicking on the comment icon. The default is set to ENABLED.
You can enable and disable alerts (i.e, immediate push notifications of the event) for your event(s) by clicking on the icon with the exclamation point. The default is set to ENABLED. Recipients will receive an email and/or mobile notifications of your event. (Note: When editing an event that has notifications enabled, all recipients will be notified of the changes you made to the event after you 'save & exit.' If you do not want to notify recipients of the event again, click on the '!' button to DISABLE notifications.)