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.
Galaxy A50 has a screen-to-body ratio of 91.6%.
Yes, Samsung Galaxy A50 does have a 3.5 mm headphone jack.
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.