If I edit a built-in clipping, will I have to reapply that edit when SD gets a maintenance update?
Generally, no. If one ships with a bug, it might get overwritten, but otherwise you’ll see a version with
(new) appended to its name added.
That said, You may find life easier if you just rename your modified versions.
Yeah, I’m thinking I’ll put all customisations in a custom folder within the Clippings folder for safe keeping.