Something is wrong and I couldn't reply so I'm going to try it this way.

I've had both of these problems.
spots - mix the color in while the icing is still in the mixer. If using day old BC (from fridge) mix again until smooth.
cracking - while mixing take some between your thumb and index finger and rub them together, I found that making sure all the ingredients were mixed well helped with the cracking, another thing smooth BC with VIVA

I'm not sure if you're talking about white spots in your buttercream or colored spots. If it's white spots, try warming your shortening in the microwave for about 1 minute on a low setting. Everything should be room temperature when mixing.

If it's colored spots, then your colors might have gone bad. Powdered colors don't mix very well with frosting.

As for the cracking, try using a little more liquid. If you're using water, try milk or 1/2 and 1/2. These give a little more softness and flavor to your frosting.

Good luck!

Michele