1/
In the ClassicPress environment, are plugin updates required regularly? Do we have to update the plugins periodically?
2/
In case the plugin no longer supports ClassicPress and goes beyond WordPress version 4.9, can we keep the plugin without updating? Especially when it is a major plugin and no longer supports ClassicPress, can we keep it at the version that is compatible and without security issues?
As for WordPress, keeping plugins updated is a good practice.
My opinion is that you can keep outdated plugin just if you can be pretty sure that new versions don’t contain security fixes. Remember that if a new plugin release is not compatible with WP 4.9.x then no update is proposed, and looks like there is nothing to update. To keep an eye closer to this you can install CPCompatibily.
If I understand correctly, once the plugin is no longer compatible with WP4.9.x, we should not keep it in CP and then consider changing it by another plugin.
Great list Simone. I’d like to add something, since @davidovic is new to ClassicPress. If you don’t find a compatible plugin for something specific that you need, don’t just run away. You can always ask on this forum about it and maybe someone has the same need and the ability to fork a plugin from WP 4.9 and maintain it for ClassicPress.
Also, there is work being done by people in this community to make a brand new directory with plugins for ClassicPress. Means, CP is evolving one step at a time.