My Last Duchess

1)
favor- an attitude of approval or liking
officious- assertive of authority in an annoyingly domineering way
munificence- larger or more generous than is usual or necessary

2)
He is speaking to the people under his wife-to-be's Duke. They are at his his house on business to talk about the wedding. The remarks he makes tell that he killed his wife because she didn't show him more love than she did anyone else. It is hinted that he will do this to his next wife, if she acts the same.

3)
He is rich and self-centered. He feels that his wife's only purpose in life should be to please him and listen to him, not anybody else. This is a dramatic irony.

4)
The Duke is definitely full of himself and feels everyone else should be full of him too. He is, however, sexually jealous that his wife flirts with other men. She isn't flirting on purpose, it's just in her personality to be so kind and happy.

5)
The Duke doesn't think of art very sincerely. He looks at art and relates it to his own life; the painting to his ex-wife, Neptune to him, and the seahorses to her joyous outlook on life and to the beauty that art really is.

6)
She was killed. It isn't relevant how she was killed, but the fact that the Duke killed her, and is now planning another wedding, is important. By telling his new wife he killed his old wife because he didn't like her hints at his craziness.