The unknown error message just tells you that an exception has occurred. If you check your SharePoint log file, you should be able to find all of the details. Usually the problem is sending an email, so make sure that your email/smtp server is
properly configured in SharePoint.
The layout of the web part is customizable with an ascx template. Unfortunately if you want to add new fields, you'll need some backend code to save the fields - so you will end up having to modify the source code.
The pages listed in the FBA Configuration are not included. They are actually for filling in variables in the email templates. The default templates only actually use the ChangePassword variable. I probably should remove the other two to
reduce confusion, but I don't want to break backwards compatibility in case somebody is using them in their email templates.