Servicing stack updates provide fixes to the servicing stack, the component that installs Windows updates. For more background information on SSUs, please see this article.
Yes, all versions of Windows and Windows Server might need an SSU to address an issue, including the latest version of Windows 10 and Windows Server.
SSUs should always be installed before any new update for Windows, including the latest cumulative update (LCU), Monthly Rollup, or Security-only update.
The latest SSU for your device can be found in ADV990001 | Latest Servicing Stack Updates.