yeah, I guess they do know the answers, but since most celebs play for charity, moreover they add popularity to the show, may be they are told the answers.
they have a trial round and I guess some questions are repeated from that . In case of Laloo ji i feel he was told all the answers and he agreed to come only if they give 1 crore .
I agree it is not the fault of SRK but the audience as only people with education back ground watch this show than the mass. So the show naturally have less people to watch it . It is all about the people what they watch and what not also whether it is targeted for the ordinary people or the educated ones.