What is ?Win32 ... ? Is this a shortcut command of some kind? (I'm not up on all the lingo yet..)
From what I can tell (and I may be wrong), it is a directive telling the compiler that you are calling a win32 library. It will still compile and run if you remove it, but you get an error when your program exits.
What does the '@4' at the end of 'GetDriveTypeA' mean?
It means the return value is 4 bytes in size. In other words a 32bit integer value.