Launching On-Prem SharePoint PowerShell
If the SharePoint commands are not recognized, it’s most likely that you need to import the SharePoint module. In order to do that, run the following command Add-PSSnapin Microsoft.SharePoint.PowerShell
Cumulative Updates for SharePoint
Every month Microsoft releases the Cumulative Updates(CU) for SharePoint. CU contains the Patches from all previous CU, hence only the latest package. The list is maintained by the Microsoft at this link https://docs.microsoft.com/en-ca/officeupdates/sharepoint-updates