Yes he will but I don't think there will be a need to use his confession.
2) What will be Ved's next move? Will he use Mahika against DK?
He is going to go ask Rano for the money. He will try and use Mahika's insecurities to his advantage.
3) Will DK find out that Disha is innocent soon? Will Disha forgive DK after the truth comes out?
Maybe Pori will think DK has come after her because he has found out she shot him. In panic, she will let drop that it was her & not Disha.
I don't think DK will ask Disha to forgive him because he is will not forgive himself - how can he ask her to forgive him after what he did.
4) Will Mahika use the mangalustra to her advantage? If yes how?
Of course. Flash it in front of Disha at the first opportunity she gets.