PHP script to write to database and integrate with PayPal

I am seeking an HTML form / PHP script that can write to a MySQL database and integrate with PayPal for secure payments to improve the functionality on my web site. Currently, each time a website user completes the existing form, the existing script writes the data to a .CSV file and also sends me an email with the data. I want this replaced (or modified if that's easier) so that the data is written to a MySQL database instead of the .CSV file and I still want to be sent an email with the data. I also need to keep all the other functionality of the PHP script (please review the included PHP script to see the extensive functionality, retention of which forms a part of the description of this project). Importantly, I want to integrate the script with PayPal and particularly with PayPal Instant Payment Notification and I want the form data to be saved in MySQL and emailed to me ONLY if the PayPal payment has been successful. It should work like this: - - - - 1 - - - - A website user completes the form and presses the "Submit Application" button. then - - - - 2 - - - - The PHP script checks that all required data has been entered. If all required data has NOT been entered, the website user receives an error message (just like the existing script) and clicks "BACK" in their browser to correct the form. then - - - - 3 - - - - When all required data has been entered, the website user is redirected to my PayPal account to make payment (as much data that can be used by PayPal as HTML Variables for Filling Out PayPal Checkout Pages Automatically should be sent at this time). then either - - - - 4 - - - - If the website user successfully makes payment via PayPal, they should be redirected to a "Success" page on my website (that I will create) and the form data saved in MySQL and also emailed to me (note that I should be able to adjust the email address and subject in the script). or - - - - 4 - - - - If the website user does not make payment via PayPal (if the attempted payment fails), they should be redirected to a "Failure" page on my website (that I will create) and, no data should be saved in MySQL and I should receive an email with a subject "Failed Application Attempt" including all the data (note that I should be able to adjust the email address and subject in the script). or - - - - 4 - - - - If the website user does not make payment via PayPal (if they cancel the process themselves) then no data should be saved in MySQL and no email should be send to me. (a) This is an urgent project that the successful Freelancer must have completed before1st June 2012. (b) The successful Freelancer will have very good written and spoken English. (c) The existing PHP script is protected by international copyright and may not be copied or distributed, in part of in whole. Ownership and copyright of all code delivered through this project will be owned by me. If any GPL code or CopyLeft code is used in the delivery of this project I must be notified of the same and/or of any derivative works, and provided copies of the base code. (d) The successful Freelancer will provide the MySQL initialisation scripts (mysqldump) of all tables required. (e) The PHP script must be written in simple functional blocks to match the workflow. Include files are preferred over large code segments. (f) The PHP script must be well documented (preferably using remarks inside the script in the same way the existing PHP script is). (g) Integration with Paypal should use the standard APIs and Paypal includes as provided on the Paypal development site / sandbox. The only modification to the includes should be the configuration variables and efforts should be made to keep as much as possible to Paypal's example use of the APIs for future maintainability. (h) A copy of the existing HTML form and PHP script is attached.