You can see the format of a drive via the terminal using diskutil list. If your /dev/disk<n> is not listed as GUID_partition_scheme you can use the command line diskutil eraseDisk /dev/disk<n> GPT JHFS+ to re-format and erase it as GUID partitioned. (See GPT terminology in dortania)
You can use CloverConfigurator to generate unique serial numbers for:
- MLB
- SystemSerialNumber
- SystemUUID
The reason you want unique serial numbers is so that things like iMessage recognize your hackintosh as a valid Mac and the tool will function. For details see this guide: an idiots guide to iMessage