Xiaomi Related Question and Answer

No, you cannot upgrade the RAM at Xiaomi Mipad 2.

Yes, it support USB OTG.

No , Mi 5S is not expected to be waterproof.

Xiaomi Mi 5S 

No, it doesn't have IR Blaster.

No.

It comes with 1 Year Manufacturer Warranty for Phone and 6 Months Warranty for in the Box Accessories

Unfortunately Redmi 3S does not contain headphones in the box.

No it doesn't comes with a wireless charger as it doesnot supports wireless charging

Unfortunately no, Redmi 3S doesn't support CDMA connection, it has only GSM support.

Heating issue is common is all the smartphones nowadays, the M iMax is not an exception to it. When played games or while using internet for too long without any pause, the place under the camera got really heated up pretty quickly. The metallic body made it really hard to hold, but after I kept it on standby for a little while, it cooled down real soon.

It takes more than 3hrs to get full charge with bundled charger :-/

No but we can use Google Cardboard on Redmi 3S. I have tested the basic google cardboard and it worked perfectly. However for better visual experience, you should buy a VR headset of a good brand.

Yes

It comes with 1 Year Manufacturer Warranty for Phone and 6 Months Warranty for in the Box Accessories

According to me, among these options Redmi Note 3 is better,  Refer this.