iPad Mini and iPad Camera Connection Kit questions
You will not be able to transfer files from a connected USB hard drive or USB memory stick using an iPad camera connection kit. First, the only files that are recognized through this connection are photos or video files, and even if it's possible to recognize and transfer those types of files from a media format other than an SD card, other card type used for digital camera media, or a connected camera, you would need to rename the files to a specific name format and directory. Secondly, the only connected USB devices that work are unpowered ones, and whether a particular USB microphone, headset, keyboard, or other such peripheral will work with your device through a USB Camera Kit may also depend on the iPad model and version of iOS you are running. (The widest range of supported devices and the iPad Camera Connection Kit seemed to work with the initial iPad release and the first version of the iOS operating system to support that iPad in Spring 2010.)
This March 20, 2012 CNET article appears to give a realistic summary of what can work with the iPad Camera Connection Kit, although they were not specifically writing about the iPad Mini and the camera connection kits with the lightning connectors.