I have taken a test for Assistant Passenger Conductor (they are hiring 7 for Oakland and 5 for Sacramento in a class scheduled to start September 8th) and before the administration everyone has to sign a non-disclosure agreement. With that said, speak to some employees about what the job really entails. That should help you think in the perspective as someone in that specific position, in this case as a CSR.
The tests will go on the premise that you do not know the specifics of the job or how necessarily to perform it. They will instead try to judge your use of logic, common sense, and sound judgment. They also may evaluate basic math and reasoning skills. I know APC's have to, but I believe CSR's also have to take the physical test upon successful completion of the written test (if a passing score is received). This tests the physical ability to perform the functions of the job, such as lifting baggage at the stated weight limit for the position or climbing up and down.
Unfortunately, giving the time of the class and other personal factors I decided to turn down the position this time around (I was looking for a career change but decided to pursue a post-grad degree instead), however your test scores are valid for one year after testing. If you pass your passing scores stay with you for a year. If you do not, then you need to wait at least a year to reapply. Based on what they discussed it sounds like it would be a rewarding place to work for many and I hope you do well on your test! Best of luck!