When you install a Mac OS upgrade there is a risk your Mavericks system will not boot. Use the autorun mode to create the drive. It will take some time to make all the settings in SFOTT (it took me perhaps 15 minutes), but it was self-explanatory and not very difficult. SFOTT is a self guiding menu-driven application. You simply double-click on SFOTT on a Mac where you both have your Mavericks Install App and your USB-drive. You first need to use SFOTT to create your bootable USB-drive (it is called “key” in SFOTT).
The 7z-file can be opened with StuffitExpander, that already Should get the file mac-mini-mavericks.7z. Where to click to get the right thing, and what gives you spyware. Warning, this is one of these horrible download pages where you don’t know I always keep these for possible future use.) A few helpful readers have shared their experiences. I suggest you read the user comments to this post. I want to first write what does not work: