OK, just one question more.
When I root phone again, I'll have in fact stock software except recovery, so I presume that I'll need to install that little guru reset ruu again after I get TAMPERED removed?
So, I need S-Off first.
then I need to get TAMPERED removed
then how to return S-On?
then again reinstall guru ruu
and here is biggest problem, how to lock it back to stand *** LOCKED *** since I won't have custom recovery and I'll probably get *** RELOCKED *** flag?
I guess I forgot about it. You DO need unlocked bootloader(you have this) and you DO need custom recovery to have SuperSU(root).
So, don't do anything else now. Flash custom recovery, root your phone and then continue to 2. in the guide(http://forum.xda-developers.com/show....php?t=2488772).
About tampered flag. Once you are S-off, you will remove this flag, and you will also be able to "LOCK" your bootloader. That's the magic of S-off, you can do this kind of things, but you have to be very careful, best is to copy paste exactly what guides say.
I posted this before:
Remove tampered flag:
Set bootloader to "LOCKED":
Yes, you can S-on when you are S-off, but let's go slowly, first do these steps.
When you are S-offed you can flash RUU's and you don't need Guru's files. After you flash your RUU, then you will go back S-on(tampered is gone from before and your bootloader is "Locked" form before) and from there it's pure stock.