Answer:
I have three feet but I cannot walk. What am I?
The faster you run, the harder it is to catch me. What am I?
I am a rock group with four members. All dead one was assassinated.
I break down buildings, I crumble mountains but you can't see me. What am I?
The shorter I am, the bigger I am. What am I?
I tell people to be careful when handling boxes.