In my first form, I am the way. Shift my lead to the end, I become a shell. Shift my lead to the end once more, and I'm the prelude to life. What am I?

Harm will befall you if your use is too rough, will also befall you if not used enough. Pearly white, or yellow or brown, if you use me enough you will not need a crown.

I have no wings but yet I fly, I have no eyes and yet I cry.

Clearly married but I'm a known wanderer. Some might remember an iconic old image of me trying a weird diet to boost my longevity. It's truly a coincidence that many now associate me with being gassy.

I take endless forms, and you all can make me. One day, I can entertain and the next day, I end relations. Pass me around, but don't overuse me. Because my form changes.