I had a cheap Chinese NAS / USB enclosure that did Torrent, web/ftp server and several other things... but was way underpowered for all that. Here is a writeup:
I just converted this NAS to use a RPi board instead of the internal ARM / Linux processor.
My RPi NAS has a 2T drive attached. Works very well so far.. not skipping or halting on video or large file transfers anymore. I am planning on adding Web and FTP server. If that is too slow then I will put the webserver on a 2nd RPi.
My ISP has very slow uplink speed 256kb so I find that it is best to host photos on a hosting site such as Photobucket or Image Shack, and then link to them in my web pages. Though my pages are very simple and plain and is a very low traffic site.
My site is hosted on my Fedora 17 box at the moment.
Also My ISP like many others blocks web servers on port 80 so I had to choose a different port.
Unless specified otherwise my response is based on the latest and fully updated Raspbian Buster w/ Desktop OS.