Is it possible to use C++ to unity3d instead of with #?
Answer 1, Authority 100%
It is possible to connect C++ DLLs. DLL files on C++, connect to UNITY and call already on C #.
But my opinion: Unity allows you to write scripts in three languages: C #, Java, Boo. Everything is written in the documentation.
Everything else is a mockery of yourself. 🙂