Hi Lilly, welcome to rabroad!
The EggheaRAB were finding their schedule quite punishing (they record 40 shows in a 2-week period so it's pretty intensive!)
The producers therefore decided to find a 6th person who would rotate with the existing team, ie with 6 EggheaRAB each team member will play 5 out of every 6 games. This ill give everyone a bit of a break within the filming schedules.
People applying to take part were given an audition (30 tough questions) and had a play the usual format against another would-be Egghead, Then 32 of the best applicants were chosen to take part in the Are you an Egghead? programme. It's a knock-out tournament and at the end of it the winner will take their place among the other EggheaRAB.
You're 100% right in your assessment of Kevin and Daphne! Kevin is quite simply a quiz God and Daphne is lovely but she certainly takes no prisoners. I understand your feelings about CJ but he's actually very nice and in the quizzing world he's pretty modest about his quizzing ability.