A textfield will take text including numbers, it is up to you to check if the user submitted a number on the server. As for changing the button text:

use CGI ':standard';
print submit( suggestion => 'RTFM' );
__DATA__
<input type="submit" name="suggestion" value="RTFM" />
[download]

cheers

tachyon

s&&rsenoyhcatreve&&&s&n.+t&"$'$`$\"$\&"&ee&&y&srve&&d&&print