I tried out in February, and indeed it does start with a 20-question agree/disagree test. Rumor has it that you need about 12 right to pass, but they won't confirm or deny that. I knew about 7 of them, and agreed with all the rest, and I passed, so it's not too hard as far as game show tests go.
I really hope you pass the test, because if you do, you're in for the time of your life in the mock game. CCs Fern and Robert make the experience a blast. They take the passers' pictures, then go to a mock game, two at a time. The beauty of this is that Robert does impressions of the nine celebrities whose names are on the game board, definitely worth the price of admission.
Note: They simulate the experience in the studio here, which includes a lot of jokes that, uh, let's just say don't make the air. If you're sensitive to that kind of thing, you'll either need to hide it well or pick a different show.
You're asked to introduce yourself while at the podium, and the host (Bergeron's stand-in, who hosts the game just as well as Tom does) will ask you a couple of questions about what you've said, so you'd best be on your toes. (Also, the "celebrities" might interact with you after you've picked them, so you definitely need to be on your toes.)
After you've played two or three questions, they tell you to be seated, so you just sit back and enjoy the rest of the festivities.
One of the most important things is to have five to seven interesting things about yourself prepared to write on your application. This is probably where the bulk of your time before the audition should be spent.
For more info, I'll defer to an acquaintance of mine, who won over $27,000 in cash and stuff two years ago. Her write-up is at
http://www.angelfire.com/80s/gameshowsteve/hsqadvice.rtfGood luck!