Yes, Redmi 6A is a dual-4G phone. You can use 2 Jio 4G sim card in Redmi 6A.
Redmi 6A has 2.0 GHz MediaTek Helio A22 quad-core processor.
Yes, Redmi 6A can play Full HD videos without any problem.
No. Redmi 6A does not have IR remote sensor. You cannot control your TV or AC with it.
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.