Write a new Drupal Module for Comments

This project is now changed from "Drupal Comments Module modification" to "Write a new Drupal Module for comments"

I am building a website based on Drupal CMS and I need a drupal expert to help me write a new Drupal module for comments.

Here is the scenario.

Authenticated users can leave comments on other user's nodes with links to own nodes.
Authenticated users receive a private message and an email notification when someone leaves a comment on their nodes.
Non authenticated users can read comments but can not leave comments.
Administrator can set permissions for Users, Authenticated Users and Admins to View Comments / Post Comments / Edit own Comments / Administer Comments

Please see attached drawing for details.

You are required to provide module files and installation instructions.

Thank you, I look forward to receiving your quotes.

Agis