Welcome johankaoko!
Lead in/lead out at wrong parts of the steel
Can you explain what the lead in and lead out is? And what is the steel? Also, exacty which Gcodetools extension did you use?
Would you be able to get a screenshot of the plasma cutter's software or window? I'm assuming it has some kind of canvas or display on the computer. But maybe not. But if there is one, and it can show the lead in/out/steel issue, that might help us as well.
Can you give us a link to the tutorials? Maybe I'll add them to my list.
Yes, as Lazur suggested, making the file as simple, or as basic as possible, might help. If there are any filters or gradients or etc., it might help if you remove those. You could put them in a hidden layer, if you need to keep them. Then send only the raw path(s) to Gcode.
If you look on the Help tab of the extension dialog, you can find the address of the forum of the creator of most of those Gcode tools. Or Extensions menu > Gcodetools > About. So if we can't figure it out, you could post over there.