Ubuntu installs Sun's JVM from the repo.
The links should work now to the docs describing the protocols for communicating with ng2 and icepanel.
you'd basically open a TCP socket connection with simple message commands.
I'll see if we can work up a design guide for how an application should act within the platform. stay tuned...
USB GPS shouldn't be a problem.
As for the Powermate, there may be some tiny configuration that needs to happen. I found this: http://tomthegeek.blogspot.com/2007_05_01_archive.html. A ng2 plugin for the powermate would be a good idea if anyone was interested.
I'm not familiar with Mitch's Sirius hardware (link?). That may require some driver/plugin work to get it to run.