2. I'm using the javascript onSubmit event handler within the form to launch a web-page in another window. I don't think you can call a Perl script with this javascript event handler.

Not that I like js solutions but you can open anyfile in a new window using any handlers, just do:

<form method="post" action="youscript.cgi" onSubmit="open('your_check_
+script.cgi')">
[download]

You can pass some extra parameters to the open function to define how you want it to appear (size scrollbars etc.)

Hope that helps.
Chris