Drop spindle spinning is a good introduction to spinning, but you most definitely do not have to master it before moving to a wheel, as they are very different motions. I prefer the wheel b/c it's easier for me than the drop spindle, and the drop spindle hurts my shoulder (too much arm raising). You might want to look for classes. The class I took taught us spindle spinning, wheel spinning, how to shop for a fleece, how to process the fleece, all that jazz. I buy what feels soft
As a spinner, I prefer my wool/fibers to be completely processed before I get them. I have no interest in cleaning, combing and carding the wool before I can do anything with it. Some people really enjoy that piece, but I find it too much work when I have a hard enough time trying to fit spinning into my routine.
But I love to spin! I haven't made anything useful, but I find it incredibly relaxing (when it goes well). I love feeling the fiber run through my fingers and onto the wheel.