Yes, Vivo Y81i does have a dedicated MicroSD card slot.
Vivo Y81i comes with 5V / 1A charger. It does not support the fast charging.
Yes, Vivo Y81i does have a notch based 6.22-inch display.
No. Vivo Y81i does not have the removable battery.
Vivo Y81i has FunTouch OS which is based on Android 8.1.