The USB port on the HG532 will work for a mobile dongle, but will not act as a media server or print server. TalkTalk have said before that they have no plans to change this. That is probably due to the fact that Tech Support wouldn't have a clue how to help with it.
If you are looking for a router that will act as a wireless print server and media server, have a look at the Fritz box 7270. I am using that and have a usb hub connected with both a printer and USB hard drive attached. I also have priority set for certain devices and applications, and it is also a DECT base station and can be configured for a committed VOIP phone attached.