If you backup your iPhone using iTunes, is it a full backup even if on the iCloud settings it's not?
It is "full" in the sense that everything that is ACTUALLY on your device is backed up (minus payment and password/security settings for obvious security reasons), but it is NOT full in the sense that not everything you see on your device is truly "on" your device. Some stuff is merely just a shortcut (for the sake of a longer explanation) to items stored in iCloud.  The details and differences of iCloud and iTunes -based backups, along with what is excluded (such as those shortcuts) in an iTunes backup are documented here, courtesy of Apple, on their support site.