Can you try it with the gas down around 12-15 CFH. It really looks like there is some kind of shielding problem. Granted you may also have an electrical fault, but black soot only happens when there is oxygen present around the weld. Even if the machine is putting out some crazy wave form that will never weld, you shouldn't be getting the soot. That just isn't caused by the electrical properties of the arc. The other symptoms may very well be a problem with the machine, but you need to isolate things one step at a time. If you have a volt meter you might want to double check the machine polarity. Make sure the torch is really positive, forget what the labels say and measure it. At the same time you can verify that the voltage matches the display. Is the wirefeed displayed about right? Hit the button for 10 seconds, without welding, and measure how much wire comes out. Someone from tech support can walk you through opening it up and checking the main connections inside the machine, if you want. Does it act like the power is weak or cutting in and out? There just really isn't all that much happening in a MIG power source. It's basically plain old DC. As long as the voltage and polarity are correct it should weld. If you can post a video, it might help, even if it's just the sound.
Long arc, short arc, heliarc and in-the-dark!