If you drop me, I'll crack, but if you smile, I'll smile back. What am I?

fun prize time! 1: When I eat, I live but when I drink, I died. What am I? 2: If you drop me, I'll crack, but if you smile, I'll smile back. What am I ? 3: Which can you keep after giving it to your friend? 4: Which letter of the alphabet goes round Great Britain? 5: What key does not lock the door? 6: What comes twice in a moment, once in a minute and never in a hundred years? I have only this, but don't use answer key (Internet)