CATALINA_HOME=path to tomcat
You should probably start using mod_jk2 instead of jk these days. mod_jk2 is better suited for multithreaded servers like apache2 and was made to replace mod_jk. It's just too hard to get people to figure out and use an almost undocumented configuration. (or step away from the autoconfig patch that was made for mod_jk)
Tomcat doesn't need to be running on 8080, 8080 is irrelivent to the working with the JK/AJP13 protocol that runs on 8009. mod_jk and mod_jk2 only connect using this but even they can be configured to use whatever port you choose. 8009 is just default. 8080 is just the connector you use if you want to reach tomcat directly via http.
Like duech said, get the mod_jk2 DSO module from the FC2 build... There shouldn't be any harm in that. But it's also very easy to build if you feel like doing so. Then you just need to set your workers2.properties file to pass off whatever uri's tomcat container should process instead of apache. You'll also need to configure apache's httpd.conf to forward all /*.jsp requests to the JK/AJP13 connector
Here's a relativly new compilation/additions/updates of howto's I did for my brother in law... Not complete but should get you going initially.