Normal Space utilization on stock S5?

Ok, so for once I have a stock, unrooted phone, AT&T S5. Ever since the last firmware upgrade I've been getting a lot of storage issues, so I started looking at things and none of it makes sense to me. I use an sdcard for just about everything, but this is how the storage breaks down at the moment on the internal storage :

16gb total
11.5 gb in 'internal storage' - meaning, as I understand, 4.5gb of OS partitions
This is where things get squirrely
1.28 gb of used user files
1.5gb free
0 gb cache (i just emptied it.)
So, about 8+gb are in unnamed 'system, but not os' files. Wtf??

The way I read this it I have 3gb of usable space - shared with cache (that within days goes to 1.5gb+) on a 16gb phone. Meanwhile, I went through and moved just about anything of size to sdcard. I have a fair number of apps, but not an extreme amount and nothing that unusual.

So, is this normal? And is there a way to figure out what is stealing that 8+gb of space without root and maybe remove it??

Part of me suspects it is some non-cache temp files - esp firmware updates (there have been a few, and they are large, and things seem to get worse after each firmware push.

Thanks,

S4 microphone problem in normal call mode (working fine in speaker mode)

Hello,
Can someone please heeeelp me, I have a Samsung s4 I9505 that I bought with a problem:
When I call someone I can hear perfectly but the other person hears a crackling sound and almost no sound but ONLY IN NORMAL CALL mode, when in SPEAKER it seems to work just fine, also with the headset the crackling sound persists.
The problem also persists in any app like viber, watsapp, voice recorder..

Things I have tried:

Restarting, factory reset
Different firmware like Kitkat 4.4 and Lollipop 5.01
Changing the charge dock with the microphone
Is there another microphone that is activated while on speaker mode than on normal call or what is the difference between normal call and speaker mode?

Unsolved mystery: can't turn on bluetooth or make "normal" USB connections

Hi,

I'm struggling with my Samsung GT-I9300 for long six days and can't get bluetooth or "normal" USB connection.

Last week, after my battery deplet I made a full charge and when turn on the phone some weird error about encryptation appeared. The phone won't boot anymore.

I have done a standard ROM flash procedure and since that, no matter what ROM I put in, phone hangs or reboot when I try to turn on bluetooth.

Besides that, "normal" USB connection isn't possible anymore. The command "adb devices" show nothing. Strangely, I can put the phone on "download mode" and flash any ROM to it.

I already tried with different cables (all Samsung original), different computers (Windows and Mac), different USB ports on the computers and nothing seems to work...

Tried several Samsung stock ROMs for GT-I9300, ArchiDroid, Cyanogen, etc.

I done extense Google research and cannot get out of this situation by myself. Now I need to receive help from the pros. :D