No. Vivo Y81i does not have the fingerprint scanner but it does support the face unlock.
Yes, Vivo Y81i does have the OTG support.
Yes, Vivo Y81i does have a dedicated MicroSD card slot.
Yes, Vivo Y81i does support GPS.
You can record up to 1080p resolution videos on Vivo Y81i. You cannot record 4K videos via Vivo Y81i.