No ETA but I can say it won't be anytime soon. We're only just getting started really.
Yes, you can do that if you want.
One fairly common approach is to make a fork of the repository in your own github account and make your game with that. You then have control over when you want to pull in new changes as they become available.
If you want to follow along with development I'll be talking about it on my patreon page.