OH 2 is beta and on its third release. It is fairly stable but still undergoing a lot of development. New features and bug fixes are released daily.
I wouldn’t say that, but given that it’s still beta you will encounter errors and need to update OH and addons more frequently than with OH 1. You will also be faced with situations where you will be having a problem and have to work through whether the problem is with OH2 or with you. So I would say you need to be more “enthusiastic” than you do with OH 1.
Fairly stable and growing more so every day, but not as stable as OH 1 yet which is pretty rock solid.
Hard to say. I don’t get my hands into the code much so I can’t say. I know it has been in work for something like a year now (maybe more) and a lot of lessons learned and architecture were taken from OH1.
There are a number of OH 2 native ones and all OH 1 native ones are supported through a compatibility adaptor. Not all of the 150+ OH 1 addons have been tested with OH 2 yet but they all should work as is.
One step away from end of life. Consequently it is rock solid, has the most documentation, and the largest community on this forum for help. But new features are not being added to the core and new addons for it are discouraged.
Major bug fixes are still applied to the core and new features and fixes are constantly being added to the addons.
There will be a time where even bug fixes stop but I don’t know if there is a definite schedule or plan. There also could be a revolt and some OH1 fans could fork it and continue development on it, though I think that is less likely.
OH 2 will continue development and once it is deemed stable and complete enough to exit beta OH 2 will become the official openHAB at which point OH 1 will be considered legacy. I don’t know when that will happen.