My Last Duchess - Help?!

Hi there. I'd like some help on these four questions. 1) What does the poem suggest? 2)What does the form mean? 3) The voice of the poem supports this because.. 4) The vocabulary suggests... for example...
I've already got something written for a couple but I'd like to know if there's anything else that I could add or make better.
1) The poem suggests that the narrator (the Duke) is an egocentric person and his wife (the Duchess) is very flirtatious with other men. He doesn't like this so he had her killed. Throughout the poem he is showing his power and wealth and wants to intimidate the reader and wants us to 'fear him'.
2) The poem is written in the dramatic monologue. This means that the narrator (the Duke) is speaking his honest thoughts and feelings. I'm not sure if this even answers the question.
3) The voice of the poem supports this because the narrator (the Duke) is telling the audience (the person representing the Count's daughter) about the Duchess and what she did to make her death happen. He is expressing his thoughts.
And then at number four I am stumped.
Thanks in advance..any help would be appreciated!