What's the difference between Luster Dust, Pedal Dust and Sparkle Dust and is this something everyone is using?

Luster dust has a hint of a sheen. Petal dust is matte finish, Sparkle dust (aka Disco Dust) is just that... sparkles.

So it's generally up to me what type of finish I prefer...........it has nothing to do with with type of icing I'm using?

I've only used them on chocolate and fondant/gumpaste. I'm not sure how they behave on icings. However, generally speaking, yes, you are correct in your thinking.

Oops! Once I used it on icing to mimic spilled champagne, I used the sparkle dust so that it would be glittery. But then I mixed it with piping gel and just kind of "spilled" it on the cake. It didn't react or anything. It did just what I wanted it to.