1) The CMAKE_INSTALL_PREFIX is defined in CMake. It's where the compiled files should be installed (when compiling the INSTALL project in Visual).
By the way, make sure you have changed it (because it points on the 'Program Files' folder by default and you don't have the rights to install files there on the recent versions of Windows). This may be the issue?
2) I'm not sure what you are actually trying to do... Can you explain it a little more? Moreover CC is built upon 'Qt' which is an abstraction library that let us compile on Windows, Linux and Mac OS. Therefore there's no platform-specific code in CC (such as calls to Windows forms or X server, etc.). There are some times dirty tricks to get the underlying structures but it's rare. Otherwise you may want to look at this: http://docs.huihoo.com/qt/solutions/4/qtwinforms/
(I just googled it).