Delivery of usernames and passwords automatically. Joomla

I'd like to have a registration form on my Joomla installation so that when a user registers they receive the website address to their specific pre-made database, the preset admin & user usernames and passwords. As noted these databases and user names will already be created prior to their registration. I just need a way to automatically deliver the details to the registeree upon completion of their request form and once it delivers the coordinated set of data, that data cannot not be redistributed to any other user. I thought that a csv file would be best, since it would be simple for me to add additional usernames/ passwords/ web addresses later on. However, I'm not sure if this would be the most secure way as it would be extremely important that that the file not be retrieved by anyone but the script. Additionally, parts of the registration form will also be used to customize the user registration details page, as well the email that is sent such as the name, address, etc.... I'd also like a copy of that to be sent to my email address. I will provide the details of the form, the email, as well as the copy for the registration details page shown after the registration form is completed. The email, registration page, and form need to be able to be customized by me at a later date. So a simple description as to what to modify and where will be needed