Yes, Vivo Y81i does support the face unlock.
Yes, Vivo Y81i does have a notch based 6.22-inch display.
No. Vivo Y81i has 2 dedicated slots for sim cards and a dedicated MicroSD card slot. You can use 2 sim cards and a memory card at the same time.
Vivo Y81i has 2GB RAM of LPDDR3 type.
Yes, Vivo Y81i does support GPS.