F451:The Seive and The Sand

I liked this section much better than the first part of the book.  I didn't understand why if Montag was so curious about books why he didn't just quit working as a fireman.  Also I didn't quite understand the whole situation with Faber. Why was he scared when Montag called him? Also why did Montag's wife freak out so much about him having books? I realize it put the life in danger but if she didn't like it couldn't she have told on him? What does Montag filling up a sieve with sand have to do with anything other than the title for this section of the book?? Another confusing thing was "Denham's Dentrifice".  What is a dentrifice and why does it keep repeating it? The book was more interesting in this section and I understood it more.  Although I was sad to hear that Clarisse actually died.  Other than that I liked this section of the book.