Yes, Redmi 6A can play Full HD videos without any problem.
Yes, Redmi 6A does have the GPS support.
No. Redmi 6A does not have IR remote sensor. You cannot control your TV or AC with it.
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.