Yes, you can play PUBG on Redmi 6A.
No. Redmi 6A does not have the removable battery. It has a nonremovable battery.
No. Redmi 6A does not have the IR remote sensor blaster.
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.