The main user testing for my thesis will focus on the website. As soon as it's complete (hopefully within the next week). Luckily there is no shortage of people to critic a website in terms of design, usability, and functionality at ITP. Paypal provides a dummy credit card number to allow testing of the donation process, so I'll be asking people to go through the process and give me feedback about the ease of making a donation.
In addition, I have access to several people who have started non-profits and/or currently work for non-profits who are going to review the content of the site and make suggestions.
Regarding the legal aspect of the project, my law student is basically my test user – every time I send her material, she evaluates it and gives me feedback about what exactly I need to change/add to make the filing process go as smoothly as possible. I rely on her to provide me with advice and suggestions based on her experience in the area.