1. Whether change of name in RTC is equal to transfer of 100% title/ownership?
No, it cannot confer title to the property, they are just revenue records which are not admissible as evidence.
2. If yes, how to establish the absolute title/ownership as the original affidavit (i.e. NOC) was submitted to the Tahsildar office.
By submitting NOC to the Tahsildar office, you cannot get the title to the property, it has to be properly registered by obtaining a registered release deed by other co-sharers relinquishing their rights in the property in your favor.
3. If no, how to get the absolute title in my favour. My sisters & Mother are ready to execute any deed in my favour.
Refer answer to Q-2
4. I have a photocopy of NOC, is it enough to prove the absolute title?
Even the original NOC will not prove your title
5. Is it valid if I take a fresh NOC from my sisters & mother at this stage (i.e.after getting RTC in my name)?
You have to get a registered release deed from your mother and sisters in your favor after which you can register the entire property in your name.
6. How the NOC (by way of affitavit/notary) are different from release deed/relinquishment deed/gift deed?
NOC is just a no objection letter without having any value as it has not suffered any stamp duty, whereas the release deed is a registered document relinquishing their rights in the property.
7. Which one among NOC/release deed/relinquishment deed/gift deed are better as far as legal title is concerned?
In this case a registered release deed will be a valid document to transfer the property in your name.
8. In a subregistrar office a clerk told me that "for execution of release deed/ relinquishment deed/gift deed, the name of the legal heir, who is releasing/ relinguishing/ gifting the property, should be there in the property document, otherwise it can not be done!!! without a name in the property document how they can release!!!" - Is this correct?
The staff of the registrar's office is misguiding you, there is no such rule, ask him to quote the relevant rules in this regard.
9. Though the RTC is in my name only, can I still take a release deed/relinquishment deed/gift deed in my favour?
Yes, even now you require their shares of property to be properly transferred in your name vide a registered document.
10. Whether release deed/relinquishment deed/gift deed can be executed at any place in Karnataka for the agricultural land situated in Chamarajanagar?
No, the deed is to be executed and registered within the jurisdiction of the property situate.
11. Also kindly provide me any information, which has bearing on my absolute ownership other than the above questions.
You have to get a registered release deed duly execute by the co-sharers by relinquishing their rights in the property in your favor after which you can get the entire property registered in your name and can make a registered title document in your name.