<em>The Divine Comedy</em> consists of 14,233 lines, divided into three cantiche (canticles): Inferno, Purgatorio and Paradiso. These represent Hell, Purgatory and Paradise. Each contains 33 cantos. However, there is an initial canto which serves as an introduction to the poem, and is generally assumed to belong to "Inferno." This brings the total number of cantos to 100.
The first purpose that Richard's soliloquy appears to serve is to reveal the motivations and personality of the character - we can see that he hates himself because he was basically a hunchback, so he was pretty self-conscious about it. He also reveals in the first scene what he intends to do throughout the play.
As for the second purpose, I'd choose the answer - it informs the audience about the background of the plot, as it gives us reasons why Richard decided to do what he did.
