@ichalter What is Einstellungen? You can find your saved passwords in the passwords manager: opera://settings/passwords
Regarding number two, only recently Chromium added a flag to allow editing of passwords. It is disabled by default, so it's not ready yet.
You can enable it at opera://flags/#edit-passwords-in-settings if you want to test it on your own risk.
To add a new password to your list of saved passwords, just go to a site and login to it. If the login info is not already saved, you will be asked if you want to save it.