Yes, Galaxy A50 has an in-display fingerprint sensor.
Yes, Galaxy A50 does have the support for the face-unlock. Besides, it also has an in-display fingerprint sensor.
No. Galaxy A50 has 2 dedicated 4G sim card slots and a dedicated MicroSD card slot. So, you can use 2 sim cards and a MicroSD card at the same time.
Yes, Samsung Galaxy A50 does have fast charging support. It comes with 15W fast charger in the box. It takes about 30 minutes only to charge the mobile from 0% to 30%.
No. Samsung Galaxy A50 does not have the LED notification light but it does have the Always-on display, so you can get notification alerts by any ways.