Are local backups of iCloud photos and camera roll redundant?
"iCloud is sync, not backup" that is an argument I've heard whenever things go wrong in iCloud syncing etc. Backup is always good. You'd value it when you'd need it.


  Does icloud photos strip any metadata or change the quality? 


None that I've observed so far. All my photos sync across iPhone and Mac and I do edits etc., on both of them. Metadata is not lost.