Does Crystal Space use Direct3D?
No, Crystal Space works with OpenGL (or software rendering) on all platforms.
Which version of Crystal Space should I use?
In almost all cases you should use the last stable release (1.0 in this case). This is the version that we tested and fully support. However, if you depend on new features that are only present in the latest development version then of course you are free to use the 1.0 development version as well. But keep in mind that this version may break from time to time and we will not be able to support you as effectively if that happens.
Do I need a C++ compiler to use Crystal Space?
Yes and no. To use the basic Crystal Space and Crystal Entity Layer source packages you need a C++ compiler. You will also need a C++ compiler to compile your own project sources. However, you can also use CELstart which is a precompiled application that contains Crystal Space and Crystal Entity Layer. And using CELstart you can make applications with Python or XML without the need for a C++ compiler.
Is there a free C++ compiler available?
How can I make maps for Crystal Space?
One of the best supported solutions for making maps is Blender. Using the powerful blender2crystal script for Blender you can export directly to Crystal Space and Crystal Entity Layer from within Blender.
Included with Crystal Space there is also an exporter script for 3dsMax. This is also well maintained and supports a lot of features in Crystal Space.