Answer:
I am the noblest musical instrument
Can not be bought, Can not be sold, Even if it's made of gold. What is it?
My second is performed by my first. A thief by the marks of my whole might be caught. What am I?
I stand in one place yet I fill a whole room. I can be filled with molten rock and come in every hue.
I can be in your body but never on your placemat. I'm always better when I'm fresh, but you'll never see me in the flesh. What am I?
A little house full of meat, no door to go in and eat.