1. The Levi's commercial borrows, or rather steals, the poem from Charles Bukowski named "The Laughing Heart."
2. Words wise, the irony appears to me in lines one and two when he claims "your life is your life, don't let it be clubbed into dank submission." These words of wisdom are directly contradicted by the corporation itself by utilizing his poem without credit or purpose other than to reach an audience to buy a pair of jeans.
3. This poem represents Bukowski's understanding of life that was gained through personal experiences that has shaped the man he became. He realized that life could either be spent as another person passing through the darkness and only seeing darkness or as a person who sees the light at the end of the tunnel despite the pitch dark surroundings and acts on the little motivation he is given to create a beneficiary factor whether it was through writing or any other positive development.
4. To answer #1 I googled "levi's go forth commercial poem" and clicked the first website where I found the poem, author and commercial. When answering #2 I googled "Charles Bukowski" and read the Wikipedia page about him.