Sory, it's me again... :S
How can I load an external model file (not the part of the "world" file) for my map? And how can I place it to the map in Blender?
For usage in Blender you better check the blender2crystal documentation as it explains how to do that. For loading external model files in a world file you can do something like:
<meshfact name="bla" file="/lev/mymodel" />