No, you're not working. The way PiP mode works for Chrome goes like this: You go fullscreen on a video, then press the multitasking button, not the home button, and the video should automatically transform to a window while the app shows up on you...
This might explain it. Seems like Aida64 was coded to request the screen to be upgraded to 4k, while still rendering the UI at 1080.
Just flashed the 4.4 firmware. First bootup was hell, everything was too slow. But after rebooting, everything seems to be smooth again.
Reboot after inital update. 1-2 reboots wouldnt hurt.
I belive it is impossible due to aspect ratios being different. If you really want 13mp at 16:9, the image would probably have to look stretched
For the Google related problems, you could try going to Settings>Accounts>Google and then Remove account. Clear the cache and data of the problematic google apps, and then sign back in.
For carrier related problems, reverting back to your old apn...