You don't mention what sort of technology you'ld like to be using. You're going to be needing a server-side technology for this one as far as I can see...
Assuming that you are going to use ASP.Net, you would submit the form and then read the values out of it using the code-behind file. A switch / select statement (depending on your chosen language) could then be used to evaluate the responses and then query a database for the correct paragraph to insert into the output document. (You would need to input the prewritten paragraphs into the database first, of course) It looks as though you might need a third party component to create a PDF document, but if you decide to use a Word document you might get away with doing it all using ASP.Net.
Could also be done using other server side technologies, of course, but they're not my area of expertise (assuming that I have one...)
Hope this helps, but it's hard to be more specific without knowing what you do and what your coding experience is...