honoluludesktop,
When I have such questions, I study the problem in reverse.
Create a file in SketchUp, with your components defined as you describe (including layers) and export it to a DXF file. Open the DXF file in an ASCII editor, and study the contents (keep the SketchUp model/components simple, or the DXF file gets too big/complicated.)
I just tried the above method with 4 rectangles, each defined as a separate component, in separate layers. I then imported the DXF file I exported, and SketchUp re-created everything just as originally drawn. The components and layers were retained as originally defined. So the DXF file has been demonstrated as viable.
I haven't studied the ASCII contents of this DXF file, but now that I know it's viable, study should reveal how the layer/component definitions are implemented.
I'm presume I understand your query correctly. If not, my apologies.
If you need an online DXF-standards description/definition (Appendix A is particularly useful):
AutoCAD 2000 DXF Reference
Taff
Layer_component_test.zip