Vivo Y81i has 2GB RAM of LPDDR3 type.
Vivo Y81i has FunTouch OS which is based on Android 8.1.
No. Vivo Y81i does not have the fingerprint scanner but it does support the face unlock.
Vivo Y81i comes with 5V / 1A charger. It does not support the fast charging.
No. Vivo Y81i does not have the front camera flash.