Hi
I have a very modified Denford CNC; I basically threw out all the electronics and replaced it with a simple stepper controller board, and control that via the parallel port using LinuxCNC. I also changed the spindle motor for a much larger Chinese 3 phase motor and inverter.
My workflow is: VariCad (outputs STL) -> MeshCAM (under Wine, outputs GCode) -> LinuxCNC. I'm very happy with this setup. I don't have Windows and only use Linux.

I have just ordered a cheap and cheerful Chinese 40W laser cutter. Once I have demonstrated that it works, I intend to do the same to this. i.e. discard the control electronics and replace it with a simple stepper controller board, and then control the machine using LinuxCNC.

I would still like to use VariCad but this time to produce .dxf files for cutting and engraving. I then need a linux application to convert these dxfs to gcode.
Question 1: Does anyone have any recommendations of suitable linux software that will do this?

Question 2: I have no idea what gcode commands are best/should be used to turn the laser on and off within LinuxCNC. Can anyone help here please?