What do a piano, a computer, and a locked door have in common?

I might be a man I might be a house I might be a hat I might be a bed The only thing for certain is that I come from the ground

One of me is built from wood, another wears a mask and hood. Though little else is quite the same, both answers share a common name.

I reach for the sky But I'm anchored to the ground When the north wind blows, I tend to cry When my brethren fall, do they make a sound? What am I?

I have a door but no lock, a space for your thoughts but no mind. I'm where your secrets are kept, but I never speak a word.