Create a PDF form with conditional fields

I need to create a PDF form where users have to fill up multiple fields. Text fields, radio buttons and checkboxs. Some of these fields should be hidden and appear based on the user previous selection. For example: One radio button filed is "Have you ever got head injury?" If the user selects "Yes" a few fields will be showen. Like "At what year?", "Are you taking medication?" In the form I have about 80 fields. Another requirment: The first field in the form is "User ID" (test field). I want to add a button to the bottom of the form that says "Submit". When the user clicks on this button, the "save as" dialog will be opened and the default name will be the text that the user filled in at the "user ID" field. The user should be able to change any of his selections at any time. You should follow the design look and feel that I will be providing.