About the pigs, it goes beyond the pigs. He transformed a chinese community from farming many pigs and killing them young for meat and little profit, to raising a few pigs and killing them old for huge profits. The drawings tatooed on the pigs' back enables this transformation, and it's that transformation that he sees as art.

About the shit machine, as he said pretty clearly, it's about creating something overly complex and totally useless while proving that was the actual intent. And then actually giving value to the shit and selling it in vacuum pack. Something you would have a hard time doing with your own shit. The conceptual idea of a "shit machine" that produces a sellable product is actually a valid comment about current society - think of all the useless crap that gets produced and sold and disposed of everyday.

And the salami floor, well that's just pure genius!