Redmi 6A has 2.0 GHz MediaTek Helio A22 quad-core processor.
Yes, Redmi 6A does have the face unlock.
No. Redmi 6A does not have the IR remote sensor blaster.
No. Redmi 6A does not have the front camera flash.
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.