What English word has three consecutive double letters?

I am the black child of a white father, a wingless bird, flying even to the clouds of heaven. I give birth to tears of mourning in pupils that meet me, even though there is no cause for grief, and at once on my birth, I am dissolved into air. What am I?

It walks on 4 when its young, walks on 2 when it's older, and walks on 3 when its very old?

People put me on the table and cut me but do not eat me. What am I?

What can you catch but never throw?

What goes up but never comes down?

I have eight fingers and two thumbs but I do not live. What Am I?

I am not alive, but I grow; I don't have lungs, but I need air; I don't have a mouth, but water kills me. What am I?

What do you answer even though it never asks you questions?

What has 88 keys?