Qt5CoreD.lib is the debug version of the library. You cannot use it as a replacement for the non-debug (release) version. If that's what your attempt to build is creating for you, then you have not configured the build to make a release version of Qt. In general, you will need both debug and release builds so you can debug your programs and provide a release version for your distribution.

IDC is used when building ActiveQt (i.e. ActiveX / COM) applications. It is installed as part of my MSVC 2013 Qt distribution, so if you install that you will get it. A .pro file to build it appears to be provided in the src/qtactiveqt/src/tools/idc directory.