Looks like you didn't read the manual or ask a few questions here in the forum first.
"1. I don't seem to have the ability to create users / permissions. Is this because I have bought the media version? I was assuming that this would be naslite with additional features but now I'm not so sure!"
There is no access control function in any present version of NASLite. We have hashed out the reasons for this in the past and at the risk of starting it all over again I will just say that it is basically counter to the underlying idea behind the OS.
"2. Also, I have a lot of data on a USB hard drive. I was thinking I could plug this into my NAS and that it would mount it on reboot and let me copy the data. But it's not mounting, and even if I could get it to, there doesn't seem to be any method of facilitating this."
NASLite does EXT2/3 only, there is no facility for mounting a FAT32 or NTFS partition on a drive. Your solution is simple, hang the drive off of a windows machine and copy the files to the what ever drive you wish on the NASLite appliance.
See the following link for further info on the distro.
http://www.serverelements.com/file.php?dl=NASLite-M2-Manual.pdfHope this helps.
Mike