I agree with @John Doe, Blender (http://www.blender.org/)is very professional (in uses Python for scripting in-case you wanted to know). Blender is capable of more than just a modeling tool. It supports modeling, animation, textures, exporting (to many popular file formats), importing, and even includes a built-in Game Engine!
Blender is open-source. This means that if you want to remove unnecessary features, you can just download it's source code and edit it (Blender is written in C++/Python).
As for a render engine, OpenGL is your best bet, DirectX is far too complex and is only (official) supported on Microsoft Windows. I'm currently creating a game engine that will use an open-source implementation of OpenGL called Mesa (http://www.mesa3d.org/).
For a professional demo video of Blender in action, checkout Big Buck Bunny and Sintel on Youtube!