You can try to remove vocals with our online app.
There is no unequivocal answer. If there is no explicit permission, then we do not recommend doing this.
No, but you can contact the user who added the track and ask him for the necessary files.
The Premium version of our vocal remover may also help you.
If your account does not contain any backing tracks, then this can be done in the Edit Profile menu. In other cases, send us an email (see below).