Don’t worry too much. There are not that many bugs, and you’ll get to know your OP-1…
About the battery meter, there’s a thread somewhere that explains that one should drain the battery to recalibrate it. But it’s not really a matter, in reality: you should be able to play for 6 hours+ without a problem 
Enjoy, dear, it’s an incredible instrument, this little one.
I always suggest to newcomers to try to come up with something in the battles:
There’s no better way to learn your instrument! And it pushes you to drop tracks, which is indeed one of the strengths of the OP-1 IMHO.