Hello Hans,
> When one installs OT, does one need Java 6 or is Java 7 enough?
The Java 1.7 provided by Apple/Oracle is buggy and generates problems so it is advised to run OmegaT with Java 1.6.
> CafeTran for instance will still require a download of Java 6 first. On OS X you can easily get a Mischmasch of different Java versions and subversions.
Indeed, especially with Mountain Lion where you don't have the possibility to easily change the order of use of your JVMs anymore.
> If Java 8 is released next year and it's really safe (and stable), you might want to install this on your system for your main tool(s). Some other (less frequently updated?) tools, however, will probably require Java 6, which will bring back the security issues.
One thing to remember is that most Java security issues are related to the browser plugin and not to the JVM. So you could run 1.8 by default (including browser plugin) and still use any other version of Java for tools that require a different version.
> PS Nice article on OT in the Toolbox!
Yes ! And the article only covered the current 2.6 version. Version 3.0 that will be released as beta next week is even more amazing !