One issue I see is that your form action from the first page goes to the second page, but your form validation code is on the first page. Your form validation has to be on the page that the form submits to (the action page).
The other issue is that you are using a before page load trigger. That would reset it when going back from page to page. You would want to trigger off of the submit button from the previous page so it doesn't get reset when going back.
The radio button seems like it would work. If you give me FTP access I can debug that and see what is going on.