Yes, Moto Z2 Play 64GB does support OTG.
Yes, Moto Z2 Play comes with the inbuilt battery.
Yes, Moto Z2 Play does have multi screen option.
Yes, Moto Z2 Play does support fast charging. It takes just 30 minutes to charge 50% battery. You can get about 8 hours of use by charging for just 15 minutes.
Yes, it comes with LED flash light with front camera.