Simple website with a questionnaire and payment

Looking to build a small web application which does the following: 1. Register. Following fields need to be entered at the time of registration - First Name - Last Name - Email id - Re-enter email id - Contact number (Country code + phone number) - Billing address - Payment information (Optional) - Captcha 2. Optional Payment at the time of registration. (This will be disabled initially but might be enabled in the future) 3. On registration, a link will be sent to the users email id to confirm and activate his account. 4. Login and password retrieval system 5. The user will be given a default page with a form to fill and submit 6. Once the user logs in he will be given a list of services that he can avail of. 7. Selecting any of the services will lead to a page which will prompt him to make a payment based on the service chosen. A service can be chosen whenever 8. Once the payment is submitted, you will be able to view the service chosen by him and assign a webform for him to fill and submit. (A sample webform is attached. Each service will have a different webform.) 9. Along with every service purchase you will be able to see a comment trail under the form submitted by the customer. 10. There must be fields which are available for administrative use only which the customers wont be able to change. 11. The payment gateway used will be "Paypal". NOTE: 1. We are looking at crisp email sending every time a registration is made, every time a new webform is filled, every time a payment is made and every time a new comment is added to the thread. 2. We are open to using open source tools as well. We already have a system in place but its shabby and doesn't work well.