I got past the empty tool path error.
I'm still trying to decide which way to go: Fusion 360 or FreeCAD. They both are not easy to learn. I do like the idea of having the CAD/CAM software on my LinuxCNC PC.
FreeCAD has its issues too. I don't know how to only select certain areas to contour. It may not be possible.
I've been reading that Fusion 360 seems to be moving toward charging for hobbyist. If that's the case, the decision is easy.
I have my LinuxCNC PC up and running now with the ASRock Mini ITX DDR3 1066 Q1900B-ITX MB, 240 GB SSD, and 16 GB DDR3 RAM. My jitter numbers are good under 16,000.
I am a hobbyist and use Fusion 360. A few weeks ago I renewed my non-commercial user's license with nothing more than a few clicks of the mouse. Never say never but I am a believer that Fusion will remain free for us hobbyists. If you still have reservations you can save your files in several different formats that FreeCad can open, which is what I do. I'll keep using it until they start charging, then I will evaluate whether it makes sense to pay up or move on.