Hi!
1. For Tobii Pro SDK related questions please contact Tobii Pro support at https://www.tobiipro.com/contact/
2. C/C++ SDKs are native which means you should link them in your C++ project settings. “Add References” only works for managed dlls in C# or C++/CLI projects.
3. If you are willing to use Tobii C++ SDK (not Tobii Pro), you have two options. One is the legacy Tobii EyeX SDK 1.8 ( http://developer.tobii.com/download-tobii-legacy-sdks/ )
The second option is the low level Stream Engine API ( http://developer.tobii.com/tobii-core-sdk/ )
Tobii Core SDK is currently only released for C#.