The third point isn't true as games don't have any benefit from the arm processor. You can't add that ram and "cpu power" to the main computing part. Especially as it is not running the OS, Sony took 2 cores from the 8 available to run the OS.

The arm is to take care of the recording the last 15 minutes played.

Where are those 15 minutes being buffered?

I think we don't know exactly and I don't know how big the files are so either

- Arm ram

- PS4 ram (3 GB reserved for "OS")

- Disk.

It goes to system ram, takes up about 1GB. The DDR3 for the arm background processor is too small, and it would take up too much hdd bandwidth, and wear it out. I do think that GDDR5 is wasted used as that and it would have been great to have 4GB DDR3 for system stuff, then the full 8GB GDDR5 and 176GB/s for games. But costs more :(

Do you have any evidence for this? I would be surprised by this as writing this to the main ram would definitely make games suffer, i.e. write load to the main ram would stop other processes (games) from having all resources available at all time (not by much, but still).

Nope. The PS4 OS has a certain HDD OS reserve. So when you buy a new console or install in a new HDD, you notice you have considerably less HDD space available than how much space you would have had if you just put the HDD in an external case and plugged it to your computer. when plugging in a new 500GB HDD to a computer, you should expect at least 465GB of free space, on the PS4 only around 408GB is available out if the box. 

That HDD reserve is how the OS caches PSN data including the Game DVR. The arm processor is basically used as a download manager and I suspect also for the game DVR/screen shot stuff. having an entirely desperate processor that overlays/underlays whatever is happening is a way to ensure stability. 

As nice as having a desperate DDR chip just for the OS, that would have complicated the system too much. Eventually it would have been cheaper for them to have just put in an extra 4GB of gddr5. But hey, having 5GB available to devs now is plenty enough, and in the next 2 years chances are that figure can go up to as much as 6.5GB. 

Not true its running also background operations, cpu benchmarks even saying the main cpu is more powerfull

http://www.cinemablend.com/games/PS4-CPU-More-Powerful-Than-Xbox-One-CPU-According-Benchmark-Test-61203.html

No matter what the arm is doing, it isn't helping making games fly in any way.

And thanks for the link, the same site features a benchmark which says Xbox One CPU is more powerful:

http://www.cinemablend.com/games/PS4-Clobbers-Xbox-One-Ubisoft-GPU-Benchmark-67877.html

i think, 1080p is important for the new consoles.

Common bro, im assuming since your screen name is digital Marine that your a 06 most likely a 51 and you dont know about upscaling. ... lets not troll please.

Edit. Ima dumbass I misread your screen name XD