Can I use the {edit_link} to POST data to a PHP script?

By the way can I use that link for sending a post from a PHP script  to add data to that entry?

Yes, you can POST submitted data to a PHP script as described here: http://www.jotform.com/help/213-Send-POST-Data-From-JotForm-Using-PHP-in-Custom-Thank-You-Page

If you have further questions, please let us know.