You can record up to 1080p resolution videos with Redmi 6.
Yes, Redmi 6 does have the 3.5mm headphone jack.
No. Redmi 6 does not have the IR blaster support.
Redmi 6 is made of industrial grade polycarbonate material.
If your budget absolutely can’t exceed the Rs. 8,000 mark, go with the Redmi 6 without any concerns whatsoever.