In case to up the things up ! Here what I've done :
My conf :
-VM windows 7 x64
-IDE eclipse mars 2 CDT 4.5
-own Build Qt 5.6
-MINGW 4.8.2

For setting up Qt env in eclipse you need to set some custom build
1) Set system variable environment QT_HOME and MINGW_HOME
2) Do not use preferences in eclipse. Could make a mess in your eclipse
3)import a project exemple Qt (Existing Code as Makefile Project)
4)Make external tools
-qmake -project working directory : source code
-qmake : idem
5)go project properties step by step
-add qmake in builder choose import and import qmake external tool. Push it up at first position (very important)
-go C\C++ Toolchain Editor. Current toolchain : MINGW GCC, Current builder GNU MAKE BUILDER (very important)
-go C\C++ Build. unable Use default build command and generate Makefiles automatically. Build command : path to your mingw32-make. build directory : your source directory
-onglet behaviour>build settings unable Stop on first Build error
-C\C++ General>Paths and symbols add includes and libs Qt. Better to add sources location
-apply and ok
6)Build to the "hammer icon"
7)Get all the makefiles debug and release from the builder command qmake
8)Get all your output files moc, ui_*.h, .o from the makefiles rules gcc and other tools Qt
-run one moretime an external tool mingw32-make to obtain the .exe in debug and release.

This is pretty straightforward put you got what you want. Don't hesitate to ask question about.
Cheers Lokl

Current troubleshoot :
-No mingw32-make clean and distclean working properly
-Cant get a shadow build yet