FAX90 Client is a free Hylafax desktop client with everything you are looking for!
You can fax any document through your Hylafax server by just printing on the virtual printer or through dragging-and-dropping a pdf document on it.
The integration with the Mac OS X Adress Book will permit you to directly access the fax number stored in it or input a new fax number on the fly.
You will be able to setup email notifications to have your Hylafax notify you when the fax documents are done, and even pre-approve a prefix to access the telephone line if your fax requires it.
This application is completely free.
From this interface it is possibile to access links to post feedback or requests; any feedback or requests are welcome.