"Modern Art"

I was familiar with the artist Pablo Picasso. I have always admire his work; and cosider him as a true art genius. I really like the way he projects emotion and meaning through his art work. I have never seen his paintings live, but whenever I encounter a picture of his paintings all I can think of is twisted beauty. Some of his paintings could possibly be considered grotesque, yet the whole composition of his paintings result in beautiful masterpieces. I had previously seen some of Jackson Pollock's art work, but I was unaware of his personal struggles. His art work is something I would consider modern art, no specific subject or meaning, open to individual interpretation. I think his work reflects his personal struggles. Most of his paintings give out a vibe of anxiety, uneasiness, and roughness. Andy Warhol's paintings were very sophisticated. I really liked the way he used pictures of iconic celebrities; he added a simple splash of color and turn them into modern art. I find death to be a very rare subject in anyone's paintings, yet it was one of Warhol's main subjects. This video made me realize that nothing in the world of art is made without a purpose. Every artist has its own agenda and follows it accordingly.
Questions:
1. Why did Picasso draw a lot of grotesque images?
2. Why Pollock seems to have one specific style?
3. Why did Pollock never have an specific subject?
4. Why was death and irony one of Warhol's main subjects?
5. How have all the artist give the term "modern art" a new meaning?