Vivo Y83 Pro has a scratch resistant display. However, it not confirmed by the brand that if it is Corning Gorilla Glass or some other technology they have used.
No. Vivo Y83 Pro does not have the fast charging support but it comes with 5V / 2A power output charger, which charges the phone quick.
Yes, Vivo Y83 Pro does have the face unlock feature.
Vivo Y83 Pro has the same aperture of f/2.0 on both sides of cameras.
Yes, Vivo Y83 Pro does have the OTG support.