Walter Benjamin's AWork of Art in the Age of Mechanical Reprodutcion

a) What is the "Aura" of a work of art.

Quite simply the "aura" is the uniqueness and personality that a piece carries with it. Benjamin says, "Aura is tied to (his) presence."

b) In Benjamin's mind, what effects did mechanical reproduction, such as film, and the camera/photography, have on the viewers perception of art?

It had many effects, one of which was that it took away the unique experience. When you go to a play, for example, the actor can modify his performance to the audience and their reactions, thus creating an individual and unique experience at each performance. However, with the creation of film, the performance is a series of performances spliced together, and then mass produced for everyone. In turn everyone becomes a critic, because everyone sees the exact same show, removing the uniqueness that the theatre provides. The same goes with the purchasing of a CD or MP3 file versus seeing an actual concert performance. No special guitar rifts, or little anecdotes from the performers, just a simple generic studio version of a piece.
The entertainment industry is trying to spur the masses, while the performers in a performance are trying to spur their audience in the moment.

c)What is meant by the passage: "For the first time in world history, mechanical reproduction emancipates the work of art from its parasitical dependence on ritual."

The artwork is set free from the rituals of the past, Benjamin wrote, "With the emancipation of the various art practices from ritual go increasing opportunities for the exhibition of their products." Meaning, that it is now not enough that the artwork simply exists. What good is a piece that is never shared? With the possibilities of mass production available, the artwork is more readily available to the masses, therefore it becomes made for the masses, and not just for the upper or more privileged classes. The art can now be produced with the intention of mass production.

d) What mechanically or otherwise reproductive processes are changing the face of art today?

With the advances in technology there are even more production processes changing the face of art today. Suddenly, Anyone who can type can be a writer by starting their own blog, or blogs, or by simply commenting on others blog's. Anyone can be a news reporter and/or camera man. Most of us carry in our pockets miniature cameras that could, and do, record what is happening around us. Which brings me to YouTube. It used to be to have a movie made and seen was quite an ordeal involving investor with deep pockets. Now with a good tag line, and decent internet connection, you can upload whatever silly thing you want to, available to anyone and everyone. Actors and actresses are popping up all over the globe.
With these advances in technology a lot of the power has been given back to the people. If there is something we don't understand, we simply "Google" it, and learn more about it. If we don't agree with the news media or how we are treated by a company or person, we blog about them until something either gets done about it or we find others who share our annoyances.
Let's not forget to mention the advancement of laser cutting technology. Again, with the internet and a computer, you can design something tangible without ever actually touching it. You can then find someone who can produce it for you, and again it is ready for the masses. The list goes on and on. We have power tools that can sense when flesh is too near to the blade and instantly shut off, we have computer aided software and CNC milling machines, even 3-d printers. Anything you can dream up, and up-load, you can create.