I would suggest you also set your self up a free opendns account and turn on most of the options.
Two reasons, it will help you control your users in the form of stopping them accessing high bandwidth source sand consuming your bandwidth -although I don't think you're going to have bandwidth issues per say.
The other thing it will help with is that you have a responsibility to prevent the cconnection being used for illegal use. Sounds very big brother, but sadly the digital economy bill does apply to what you are doing.
You can't possibly know what is installed on each computer on your network, what they are going to download. Etc,
We use pfsense in two locations, one is holiday apartments and the other is a leisure facility, you'll be surprised what appears on the blocked domains list report generated by opendns. And these are family environments…...oooooo
Good luck with your project.