3 questions on PerlScript

1)Do I have to install something extra to run PerlScript within 
my asp?

2)If I wish the language of the page to be completely in
perlscript I include this line

<%@Language="PerlScript">

any subsequent change to a different language can be 
accomplished within <Script> tags

3)Do I need to change the file extension if the file is
completely coded in PerlScript or will it remain .asp?