Maybe I can outline what gets updated in the new releases and what not, based on
the basic directory structure of the components.

1) OpenJUMP: here the .jars get updated. You'll probably not have a problem
using just the latest release version of the tool anyway. The only thing you
might be missing is the various settings/entries in the GUI that the tool
usually remembers (such as added EPSG codes etc.). You can fix that by copying
the workbench-state.xml over to the new package.

2) config service: What gets updated here is mainly the .jars. What gets also
updated is the WEB-INF/conf/template.war, where also the .jars inside get
updated. Everything else stays constant.

Let me also outline a possible update mechanism, in terms of simple steps that
you can use to update an existing config service instance. I'm assuming that you
didn't manually alter the template.war!

Let $cfgdir be the directory where the config service was previously deployed.
Then do the following:

0) Stop the tomcat.
1) Move the $cfgdir to a backup location (here referenced as $backup)
2) Unzip the new cfg-newrelease.war to $cfgdir.
3) Copy the $backup/WEB-INF/web.xml over to $cfgdir/WEB-INF/web.xml
4) Copy the $backup/WEB-INF/conf/services over to $cfgdir/WEB-INF/conf/services
5) Copy the $backup/WEB-INF/conf/users over to $cfgdir/WEB-INF/conf/users
6) Restart the tomcat.

That should be it. If you know/notice that I'm missing something here, please
let me know about it, so we can document the proper update procedure here.