only selected objects will get exported. if you want to export the whole scene, you just have to select all objects by pressing [a] before exporting.
a texture size of 2000x2000 is not ideal for gamestudio. better use 2048x2048.
blender_level_exporter.zip make sure you use this latest version. it can handle map compiler and engine paths with spaces in them. it sounds like this has caused your new error message.