2 new functions for Website

We have our website under construction. Now we need to functions Function 1 ========= When a person buys something from another user, we want to give him the possibility to add a comment/question. So the task is to add a textfield within the buying process and deliver the text to the seller after a succesfull payment (via paypal) using the intern message system Function 2 ========= A simple form where user can send links by mail to any person. Similar to the function on this page: [login to view URL] (see also attached file) The webpage is based on CakePHP, so knowledge about MVC-architecture is necessary