ONOS stands for "Open Network Operating System". We realize it's a bit confusing, considering ON.Lab stands for "Open Networking Laboratory"!
We currently actively support Ubuntu and OS X. ONOS works with Oracle Java 1.8, but OpenJDK should work as well.
Please check our Jira to see what's in progress. If what you are looking for isn't there, you can always help by contributing!
Thank you for your interest! The Developer's Guide should give you the details of what's involved.
You can find the latest documentation on the ONOS Documentation homepage. The tutorials and sample code can be found in Tutorials and Walkthroughs.