I think the first one is showing that there is a target on peace and that people are trying (inadvertently or not) to get rid of it. The dove with the green is a biblical reference to Noah sending out the dove after the 40 day and 40 night storm. The dove in the picture has a kevlar vest on which leads me to believe that people are trying to keep the dove (peace) alive and well. I agree that people are trying to keep piece alive, but it's an every day struggle.
The next one shows a girl floating away using balloons over the Israeli/Palestinian conflict wall. I think this painting shows that it takes only a child's mind set to get past the wall. The fact that the girl is a shadow shows me that she is a figurative representation of someone, possibly an adult. This painting is used to poke fun at the wall and show the makers of the wall that a giant physical structure can't hold the essence or imagination of a child, or an adult with a child's mindset. I like this one and am in favor of the idea that imagination sets people free.
The next piece is a rock with hieroglyphs on them, fashioned like a fossil found from ancient times. The person in the picture has a shopping cart, which is trying to show that, even since ancient times, people have gone to the grocery store for food and sustenance. The image is trying to show that humans have lost their ability to provide for themselves and live off the land. I agree that people no longer are able to provide for themselves without help from stores.
The next picture is simply a big flower in the middle of a concrete jungle. This picture shows that even in a dull, mundane environment, life and color can blossom. The stem of the flower is off around the corner which shows that the beginning of new life is closer than you think. I agree that interesting things are closer than then may seem.
The last one is of a dog about to shoot a phonograph with a grenade launcher. I think that the author is trying to convey that technology (the grenade launcher) is developing too fast (even the dog is able to use it) and that it's destroying, or about to destroy, old things that we should cherish (the phonograph). I agree that the boom in technology is making us forget the good ol' days and everything that goes along with them.
I think that graffiti is as much a display of art as a painting or a sculpture. Art is in the eye of the beholder and it is an expression of the artist. If the artist so wishes to make his art using spray paint on a public wall, I think they have every right to do so. I think that artists and authors use pen names to shield themselves from public criticism and it allows them to use the guise of a fake name to say what they really feel. If they use a different name, they don't have to censor themselves.
I think the importance of an author or artist to publicize their work is only a great or a small as the artist wishes. If they want to get their work out in public, they certainly should, but if they want to keep their work private, that is their prerogative.