This week's book giveaway is in the OCPJP forum. We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line! See this thread for details.
Second, the answers to these questions would be too long for a forum like this. The best way to get an understanding of these things is to read the servlet spec itself. There is a link in my signature. If there one thing in there that you're having a hard time getting your head around, by all means, come on back and ask.