Adventures of Huckleberry Finn Questions

Bring on the tough stuff - there’s not just one right answer.

There is a lot of criticism surrounding the last few chapters of the book, where Tom Sawyer comes into play. Many believe the playfulness of these chapters ruins the serious message of the book. On the other hand, it does raise some bigger questions that we wouldn’t get without Tom. What do you think?
The biggest big picture question of all is this: how does Huck effectively change over the course of the novel? Or does he change at all?
How does the comic nature of Huck’s youthful narration work together with the book’s examination of racism and slavery? How is it possible that such serious issues can be addressed with a seemingly light tone?
What’s up with what we called the "Introductory Snippets" at the beginning of the novel? How could Twain say that there is no plot and no moral to his story?
Adventures of Huckleberry Finn was criticized for its rendering of dialect. Is the representation of how people actually speak necessary? Does it add anything to the novel?