The Question and Answer section for In Cold Blood is a great resource to ask questions, find answers, and discuss the novel.
I see no evidence in Part I of Mr. Clutter singing in Part I of the novel. Perry, however, sings multiple times. Are you sure you've used the correct character in your question.
From his choice of sixteen year old brides, we can infer a few different things about Dick. First, you're correct, he seems to like younger women.... particularly teenage girls. Dick's interest in young girls illustrates his need to be in charge,...
Unfortunately I can't think of any songs that relate to the very dark themes of this book.