1.) Do you really have ntddk.h in MinGW's include-folder or in include\ddk? For me it's the second. You should change #include <ntddk.h> to #include <ddk/ntddk.h> (works for me.
2.) You most likely do not have a c, but a c++-project. Remove the cpp-file from project, change the file-ending to c and readd it.
Your second question has nothing to do with C::B, and normally your topic would be locked or silently removed.
But your first question is a mix of a lack of knowledge and a C::B-issue.
That's the cause, why I give you some hints.