Thank you very much Shabbypenguin for quick reply
So basically rooting a phone to gain super user does not need flashing with shabbymod.
Few more questions:
1. Will rooted (not shabbymoded) phone be able to receive OTA updates?
Yes you will get updates still, however being able to apply them may be reduced if you remove certain bloatware that they would rather you keep.
2. Will rooting (not shabbymoding) void warranty? If yes then can the phone be easily unrooted?
Any modification can result in voiding warrenty, but you can use Odin and put stock image back on no problem.
3. In a rooted device (not shabbymoded) other than superuser level, will there be any other difference in the phone as compared to how it is now? (in terms of features and performance).
In stock form the phone was a little laggy, and just not perfect in my experience. Rooting it does not change that, removing bloat will help though. Some of the shabby mod tweaks are all "under the hood" type that you will not see or notice, but the affects of them are very evident.
Thanks again for your help