1.  The 5 severity levels in Zabbix are as follows:
   • Disaster
   • High
   • Average
   • Warning
   • Information
   • Not classified
2. Yes, Zabbix can send messages to users or groups, or both and configuration is done under the tab configuration—Actions
3. Yes, for every item, there is a preprocessing tab that allows us to make some changes before Zabbix stores the data in the database.