The tests are all multiple answer.
As Don says, just be yourself. The recruiters and psychologists have lots of experience in their job, they spot BS a mile off, and that is an instant Fail.
As for prep, I honestly did no prep. The tests are easy enough that even if you don't know the answer immediately, you should be able to hazard a good guess.
Be honest, think before you speak, and be respectful of your fellow applicants. There are enough vacancies to take everyone on your selection.
The recruiters are VERY positive. The only person who can fail your interview is YOU.
So come along, show them that they can sit beside you for 8 hours in a cockpit, and in the sim let your performance confirm what your logbook says.
Good luck.