In the study of Richard III, can someone suggest a list of key passages that should particularly merit greater focus?I know for a fact that his...

You are right in your hunch that Richard's opening
soliloquy is important. Note what this shows us about his character and the theme of
evil that runs through the play and his person. In addition though, you might like to
examine one key theme and how this theme is presented through the various speeches of
Richard III. The way that he uses and abuses language to achieve his goals and purposes
is incredible, and well worthy of some serious study. Most interestingly of course is
how he woos his wife and moves her from absolutely hating him to actually loving him and
willing to marry him in Act I scene 2. You will definitely want to focus on the kind of
language that Richard uses in this scene to woo her. There are of course plenty of other
scenes in which Richard shows the power of langauge to
manipulate.

However, in addition to this important theme, a
very important speech is made in Act V scene 5, when we see Richard undergoing a very
poignant moment of self-realisation after seeing the ghosts that have haunted
him:

The
lights burn blue. It is now dead midnight.
Cold fearful drops stand on my
trembling flesh.
What do I fear? Myself? There’s none else
by.
Richard loves Richard; that is, I am I.
Is there a murderer
here? No. Yes, I am.
Then fly! What, from myself? Great reason.
Why:
Lest I revenge. Myself upon myself?
Alack, I love myself.
Wherefore? For any good
That I myself have done unto myself?
O no,
alas, I rather hate myself
For hateful deeds committed by myself.
I
am a villain.

Note the
element of self-doubt and self-criticism in this soliloquy. Attempting to calm himself
from the fear of the ghosts, he tries to remind himself that he is alone and therefore
safe. Yet the horror returns, yet more strongly, when he realises that he is the most
dangerous person that he could be left with, as a mass murderer. Note the way that at
the beginning of the play Richard said he was determined to "be a villain." Here we see
Richard's realisation that he has succeeded in this goal and the rather mixed feelings
he has as a result. You will want to focus on the internal conflict that is displayed
through this speech.