Let me answer point No 3 first because your case will befall without it even if you are answered positively for the rest of the queries. If you cannot produce any witness by which you can prove your case then how you would convince the court to believe that the cause of action aroused on that day. So no your case no matter how genuine or strong it might be if you cannot prove that case before court there is no relief that you can get from the court.
Having said that let me come to the remaining questions 1. you can file the defamation case within a period of 1 year from the date of cause of action i,e when you were defamed by libel or slang. But since the supreme court has now extended the limitation period so you can file the case even after one year but that will depend on the date on which the apex court vacate the order of suspension of limitation period. You can take advice from your lawyer at the time when you finally decide to file the case
2. legal option - file a case, it can be both case of civil and criminal defamation and you can get both compensation as well as punishment for the accused.
4. For procedural matter it is better that it may be left with your lawyer since the whole process has to be undertaken by your lawyer unless you want to file that case in person in which case you can do it too.
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You can file criminal defamation case
If you want legal advise then you can call me on mobile no 9359867870
Advocate IRFAN SHAIKH