SPEntryPage modify the OOTB version?

Hi,

The articles in the community show examples of modifying the SPEntryPage script include to customize behaviour such as redirecting users to a specific portal page based on role after login.  I did find a KB article (https://support.servicenow.com/kb?id=kb_article_view&sysparm_article=KB0869746) that mentions "...cloning the OOB SPEntryPage" and then setting the system properties to reference the clone instead of the OOTB script.

1. Is it best practices to work on this script directly as I've seen or made a copy?

2. How do you make the copy.  I noticed just creating a new script include (and copying the script) creates a script include where the package is "Global" but the OOTB script include has "Service Portal - Core"

3. Whether you modify the OOTB script include or create a copy is this overwritten when you upgrade to a new major version (e.g., Tokyo to Vancouver)?

Thanks a lot.

Regards,

Henry