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.
That depends on how you are starting tomcat. Tomcat is just a java app, so you can use the java command line arguments to set the VM size (-Xms -Xmx). Chances are you are using a script to start Tomcat so you'll have to do some digging to figure out how it sets memory arguments.