Thanks for the feedback. 1. My email id is on the FAQ page, but I'll add a link to the footer shortly. 2. I decided to go with Paypal's default button because I felt that it will more more easily recognizable. 3. I guess you are getting the 500 error because you have not added any employment/education details. I will look into it shortly. 4. It is a one-time payment. I have just updated the text to clarify it.