Answers to your questions:
1. Settlement is a big risk. There are cases where the girl withdrew from the settlement even when the mutual consent petition was already filed. Also, this settlement is the main cause of increase in this extortion racket. Still, depending on the situation you can decide on that.
2. She CAN file DV now. But do catch all the points there. DV on the same allegations is not allowed legally as it would count to Double Jeopardy, but that is not automatic, you will have to use these clauses to contest if she files DV too… Also, while by law, 498 A can be EXTRACTED out of DV, reverse is not true.
3. First you have to PROVE that her allegations are false. Only then you can sue her. Moreover, proving that requires you to undergo a trial which can last for years.
4. There is no limit for 498 A cases. They can drag for as many years as litigants have the capacity.
I know it is difficult to attend courts and it also causes embarassment, but then you are not alone,. all of us are sailing in the same boat. Don’t worry, only through mental strength can you ultimately win over the opponents. So, keep strength and keep fighting.