Root upgrading or changing firmware

[bombayboyzone]

Hey guys im a bit confused as to how we can upgrade firmware. When I try through kies it does not allow. How ever I see a lot of websites offering firmwares with various fixes. My questions are

1) Are there unofficial firmwares safe?

2) Where can we get official firmwares?

3) Does unofficial firmwares void warranty. Does it erase ur IMEI?

4) Does it require rooting?

 

[barqers]

1) Yes they are safe using ODIN. Because it won't alter your partitions that could damage the phone.

2) xda forums or samfirmware.com

3) it will void the warranty, but you can always reflash the stock rom and they won't know.

4) it doesn't require rooting, but rooting is probably a good idea!