Can You Guess The Author Before David?

Every Christmas I get my brother a book and give him clues to guess what it is.
And for the past few Christmas Eves I've invited my readers to decipher the clues along with him.
Know the answer to #3? Then post it in the Comments!
Together perhaps you'll figure out what's in his present before David does.
The rules are no Googling, rather only offering the answers you know and pooling mental resources with other readers.
Below is the text of his card:

There is no way you can guess this year’s book title. However, you definitely know its author. The following are nine clues as to the letters in his name, and one unclue which will only throw you off. You’ll have to figure out which isn’t actually a clue.

1. According to Groucho Marx, this kind of person is a critic. The letter that occurs three times in this kind of person might be the first letter in his name.

2. Three Stooges. Marx Brothers. Beatles. Such different acts, yet when we talk about them, their names all begin with the same letter. If Clue #1 is a fake, then this letter is the first in his name. If not, it’s the second.

3. According to Norm MacDonald, this organ only understands violence. One day, he says, it will attack and kill you. Today, its first letter is probably the third letter in our mystery.

4. What’s the difference between “then” and “than”? One of them has a letter to share with us.

5. This famous comedian refused to receive the Mark Twain Prize for several years because of the kind of language that was used at the event. He eventually accepted. The third letter in his last name might go here.

6. The seventh element on the Periodic Table, and something you’re inhaling right now, might be helpful here.

7. If we’re not talking about Bob Dylan’s Modern Times, then we must be talking about this man’s movie. His first and last names match, making this clue so obvious it seems like it must be the unclue.

8. Your mouth can speak any letter, but this is the only one your lips can spell. Enjoy not snickering over this joke in front of Grandpa.

9. This letter is redundant. It’s occurred somewhere in the name already, and occurs for the second time here. Is it the last letter?

10. If this is the last letter in his name, then it’s the first in the title of the movie that beat your beloved There Will Be Blood for Best Picture at the Oscars in February, 2008.

Figure any of them out? Or the author's name? Feel free to guess below!