from what I read in previous thread the bugs that make me worried are:

1. some people have really bad SOT. battery finished by half day with really bad battery drain
2. wifi sometimes not working
3. poor reception. this also leads to bad battery drain.
4. notifications not working properly (need to open app before notification comes in)

but what worries me is that very inconsistent, some people no problems but some really unlucky hehehehhe 

For delay watsapp n sync try lock it to memory will helps.
I can c there is a lock icon when u lock it to memory

This phone keep awake.... I suspect is Gmail. Now reset again and set as new phone.  No more restore from previous mi4i apps.

But the data traffic always show got traffic... Suppose should not be when the phone idle

If not mistaken, advanced manual mode only available on Mi flagship line ups. Mi3, Mi4, Mi4i, Mi Mi Note/Pro.

These includes
- manual ISO
- manual shutter speed,
- manual focus distance
- manual control over white balance adjust in kelvin units (from 2000k ~ 8000k)
- focus peaking

you can't control aperture bro 
smartphone aperture is fixed, unlike DSLR. Redmi Note 2's aperture fixed at f/2.2

yup very likely, look like it need shielding
AP roms keke
recommended to clean wipe, then flash roms from official site
try to turn off auto brightness, i set 50%
i suspect i save 10% xtra power

need u guyz to help verified

Hmm you are mi fan as well

Yup most of my phones all set to half 50-60% brightness, if more than that, surfing browser lowyat the battery can notice dropping as faster

any improvement ?