That's a lot of different characters. Bob might have something unique to say to each of them, but I doubt it. He's too focused on himself being the victim that everything he would say to those characters would be along the same lines. Bob Ewell would likely accuse most of those people of intentionally finding ways to make his life even more miserable than it currently is. The court trial is just another event that allows Bob to play the victim.
I do agree with the previous posts that state that no matter what Bob said it would be loaded with curse words. What's sad is that Bob would address and question his own daughter in this method as well. The initial question asks what Bob would ask each of those people, so I believe that all of Bob's questions would still highlight how he believes other people's actions are intentionally making him look bad. Perhaps Bob would ask Mayella, "How could you do this to me?" Or perhaps, "What were you thinking inviting Tom Robinson into our house?"
I think anybody closely associated with Atticus could get the same question. "Do you think you are so much better than me?" That's basically what Bob asks Atticus anyway.
“Too proud to fight, you nigger-lovin‘ bastard?”
Bob feels that he and his family are being persecuted by Atticus and the court system, so Bob might simply ask Atticus or the judge "Why are you persecuting me?" Bob also feels that the court case is unfairly portraying him, so he could ask the judge why he is allowing these courtroom antics to happen.
As for what Bob might ask Boo Radley, I believe that Bob might say something like "What are you doing here?" He would say that just as Boo arrives to save Jem and Scout from Bob's evil intentions.