In password security, the longer the better. With a password manager, using more than 24 characters is simple. Unless, of course, the secure password is not accepted due to its length. (In this case, through STOVE.)
Possibly indicating cleartext storage of a limited field (which is an absolute no-go), or suboptimal or lacking security practices.
No, it most definitely does not need to be private. The idea with salt is to invalidate rainbow tables. If you’re “keeping it private” it’s just another password.
https://en.wikipedia.org/wiki/Salt_(cryptography)