CATALINA_OPTS is a better place than JAVA_OPTS.
The former is only used when actually starting the Tomcat instance.
JAVA_OPTS is also used to start JVMs that only interact with Tomcat (for example the JVM instance that is used to send the shutdown-message to a running Tomcat instance).
Those JVMs usually don't need so much memory, also if you specify a jmxport on JAVA_OPT you'll get an error (port in use) when tryng to stop the JVM.
On RHEL there isn't the directory /webapps/ROOT, so this cause some errors and the worst it's the failing of the following chown, so webapps directory stay to root.