Help I9100G shall i proceed this firmware upgrade?

[darklove]

Hello there

my phone info :
GT-I9100G
PDA: I9100GJPKH8
Phone: I9100GDZKH5
CSC:I9100GOJPKG7
Build info: Mon Aug 29 14:04:52 KST 2011

am so beginner in phone flashing stuffs
i've been trying to check always to see if i can upgrade the firmware by the phone or by Kies
trying update software on Phone = ( Unable to connect )
trying to check for new firmware on Kies = ( Kies doesn't support your device )

i did so many researches and i found a post here talking about that code that check the original CSC code *#272*[Device IMEI code with no brackets]#

i did checked mine and i found out that i got :
Sales Code: XSG

out of carious ...
i select EGY and i pressed install i had wiped data and phone reset which i got no problem with that since i wanna learn on my own phone
and after the phone reboot i had no problems with it at all it was doing well and great.

after that i opened Kies and i saw this ...

My questions is :
1- was the changing of the Sales Code wrong idea ?
1- should i proceed this update after i changed the Sales Code to EGY ?
2- is this is the update of ICS ?
3- what if i fail with the upgrade is there is anyway to go back to my original ROM?
4- any harm will cause for the phone ?

Any answer would be Appreciated ,,,
Thank you in Advance

 

[Shotgun84]

Changing the csc won't have done any harm. The update is ics so I'd go for it. In the unlikely event the update did fail you should be able to manually flash your original or updated firmware using Odin.