This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
This is up to the servlet container. It can put the class files anywhere it has a classloader for. If you mean where does it put the Java source code there's no requirement to put it anywhere - it can be discarded as soon as compilation is complete. To find out more you will need to consult the documentation for your JSP engine.