Welcome to the JavaRanch, Bosch!
As Ulf has said, the idea that
you should use Apache to serve static content for
J2EE webapps is an outdated old wives tale.
However, Apache is VERY useful when integrated with Tomcat. It provides "one-stop shopping" for a mixed bag of J2EE and non-J2EE (
e.g., python, php, cgi) webapps. It avoids the issue where Tomcat cannot own TCP/IP ports 80 and 443 without running under (dangerous) root permissions. It can act as a load balancer for multiple Tomcat instances. It can proxy for a Tomcat that's on a machine not directly attached to the open Internet.
mod_jk, however, is not the only way to link Apache and Tomcat. I use mod_proxy. There's also a third mechanism, I think, though I forget what it is.
You are looking at documentation that is so old it's probably mixed with dinosaur bones. The current production release of Tomcat is Tomcat7 and the current Apache httpd server release is 2.4.