Peer Review Requested

I've created my first GH parametric model.  I'd appreciate people taking a look at it and letting me know ways to improve the way I've built the model.

Also, I have these specific questions:

1. In the top skin of the workbench, I want the holes to be an option.  I've got a boolean toogle for holes on top skin.  But I'm not sure how to make that turn the holes logic on and off.
2. How do I get the GH model to put Rhino elements into the Rhino file automatically.  I see how I can add items manually using the bake command.  Is there a way that does not require user interaction.
3. How can I set the Layer through GH.
4. The final output of this model is create CNC files to be used on a plywood router.  I'm using VCarve to create the CNC files.  There are multiple steps from GH to final CNC files.  Does anyone have a simplified process for this.  For example, here's some of the things that I'm doing manually now:
   1. Flattening all of the pieces of the model.  Ensuring that all pieces are layed out flat on the XY plane.
   2. Then moving the pieces together in the XY plane so they will fit on a 4'x8' board.

The GH file is attached.  The final model can be found at https://github.com/GoPlywood/UltimateWorkbench.  

Thanks

Scott