No. Redmi 6A does not have the gorilla glass protection.
Yes, Redmi 6A does have the face unlock.
No. Redmi 6A does not have the IR remote sensor blaster.
No. Redmi 6A has 2 dedicated sim card slots and a dedicated MicroSD card slot. So, you can use 2 sim cards and a memory card at the same time.
The Redmi 6A is a fairly good update to the Redmi 5A, which itself was barely any different compared to the Redmi 4A. You now get a tall screen, better processor, and improved polish overall.