The main character, "V" is almost always depicted as wearing a Guy Fawkes
mask, except for one scene in which he exchanges the Guy Fawkes for a clown
mask of sorts.
An important fact in the plot of "V for Vendetta" is that the reader never gets a clear view of V's true face. In some parts of the book, one can see the outline of his head or ears; however, this is pretty much the most that one ever sees of his face. At one point another character describes him as ugly, but then upon reexamination finds that he is "beautiful" Looking through the book for clues to V's identity brings up little else.
What can be learned about V is that he was originally imprisoned at the Larkhill camp, where he was injected with an experimental hormone mixture which apparently made him gain intelligence and a "magnetic personality", but also drove him insane. Because of his personality, he was able to convince his captors to supply him with fertilizer and paint thinner, which he then used to create napalm, mustard gas etc. After his preparations were complete, V then caused an explosion that destroyed the camp and subsequently disappeared.
Another interesting thing about "V" is that in a couple of instances in the book when he kills someone, it is unclear what he actually kills them with. For example at one point V kills two guards in the dark on a train. There is no sound from the killing and it appears as though he killed them with his fingers by driving them through someone's chest. At another point he kills a man by driving a "blunt object" through a man's chest "with incredible force". I am uncertain, but it appears that V actually killed the man with either the nose or chin of his mask, as his hands were empty at the time.
Also, the Latin saying "ave atque vale" features prominently as it is said by the dying V to his successor.
About the art- there are no written "sounds" in the entire graphic novel- the sound effects are implicit in the drawings themselves and are hence omitted