I am the website developer for a government office that displays access to a 165,000 entry SQL database as well as takes confidential information over the web. I also have my own 'side' business that I've been working on as well. I am highly fluent with HTML/5, CSS/3, Javascript, Jquery, AJAX, ADO, ASP, PHP, C#, C++, VB, SQL, etc. etc.
I think you're going to want at least 2 if not 3 or 4 people depending on the number of hours each person can volunteer to the project, the size and number of changes and the ability of the programmer.