DOOL: Question regarding Chad?

Smartypants is correct, Kate and Madeline were call girls for Stefano many years ago. Madeline went on to law school and became a judge. Stefano was looking for a tape that would incriminate him in the death of a senator, so he had Kate dress up looking like Madeline and go into her safety deposit box to retrieve the evidence. When Kate was going through the envelope she found the birth certificate and kept it from Stefano and was waiting for the right time to reveal. Chad observed Madeline and Kate arguing and their refusal for Chad and Will to hang out and be friends so the boys did some investigating. Will overheard Kate talking to Madeline about their working days and went straight to Chad with it. Chad and Madeline were on the pier arguing about her past and Chad started up the stairs to get away with Madeline chasing behind him. In trying to get away from her Madeline fell back off the stairs and died. D.A. Woods couldn't accept her death and blamed Chad so he pretty much disowned him and has been away for a long time. Kate felt bad for Chad and tried to get Chad to work for Stefano but couldn't work it out. Finally Kate decided to send the certificate to Chad anonymously but Chad believes she knew all along and was the one who sent it.

You are correct, the story lines have been very slow and you only missed some of the small details that can easily be caught up on.

Stefano was Madeline (Chad's mom) and Kate's pimp when they were hookers. They haven't really said anything, but the viewers can assume that Stefano took Madeline for a "test drive" before he sent her out to other men.

Madeline died and Chad's supposed dad blames him for it, we don't see him anymore.

I'm not sure what you're talking about but Stephano isn't my dad.