Check out the school specific threads in the sub forum - most of them will have the exact prompts and schools usually don't change them between years.
Exactly. That thread's information is invaluable.
http://forums.studentdoctor.net/forums/2014-2015-allopathic-school-specific-discussions.974/
The secondary prompts are right at the top of the first page, but on some, be prepared to have to scroll down a few, in case it wasn't updated. Gettheleadout did a great job, however, and you should be golden.
What else should you know?
Your secondaries aren't simply isolated essays. If ADCOMS read your essay, and it doesn't sound like the "you" of your personal statement and app, then that's a problem.
Often, you won't really have a good chance to "represent" the "you" of your primary, but if you can, your ENTIRE packet (primary, secondary, etc.), should clearly and consistently demonstrate a single person, their values, their passions, and their voice.
Thus, during your primaries, try to really understand and showcase the "you" that you would like to present to ADCOMs, and faithfully/truthfully express that same person in your secondaries and interviews.
Just something to keep in mind.