From checking out the PDF file in the sources area, it looks like it’s a function of the print driver. Possibly a menu selection or different driver needs to be installed for faxing capabilities?
As for the server. Depends on what kind of hardware its on as to if it can handle it and what else is installed on it. If there’s nothing else, and it’s a small business, and you’re not faxing 50 – 60 pages / fax, you should be ok running it. If it’s just a DC doing fileshareing, I’d say you should be ok. Take a base line of the server prior to setting up the fax solution and have a few select users start to use the fax capabilities, and monitor it again. If the new monitor readings spike a lot higher than the original base line, you know you’ll need a new server.

For light duty faxing, I don’t think it should be a problem unless the driver does some type of document converstion on the server as opposed to the workstation.