CP Appointment Calendar allows you to define "available" time slots that can be booked by the website visitors.
A: The product's page contains detailed information about each field and customization:
A: The previously installed version of the plugin (if any) must be deleted before installing a new downloaded version.
This is a safe step, the plugin's data and settings won't be lost during the process.
Another alternative is to overwrite the plugin files through a FTP connection. This is also a safe step.