Hi Chank Hervella,
After studying your .xml and all the documents I have to backtrack on my earlier posting…
As far as I am aware (last time I looked) the UC100 Mach3 plugin does not support the Mach3 M11/M10 command set and if that is still the case then it rules out using the Vectric Laser Post Processor as a resolution to the excess laser burn at the start and end of the toolpaths. (As you said earlier, you tried it and it did not work).
As for the laser streaking – because your DL445 is totally interfaced with the 840 controller rather than your PC it would perhaps be unwise to make any electrical modifications without the approval or endorsement of Stepcraft / Stoneycnc. So, I think you need to be talking directly to Stepcraft about the streaking issue and get their suggestions on the way forward here.
Tweakie.