Although some schools will ask for an essay about some current hot-button medical issue, others will ask completely off-the-wall questions designed to test the student's critical thinking and communication skills. For one school, I wrote an essay about whether pharmacies should sell tobacco products and was then called upon to defend my position in the interview.
It's important to be reasonably conversant in current issues - i.e., emergency contraception, pseudoephedrine regulation, Medicare D, or medication errors - but it might be more important to focus on one's motivations for choosing pharmacy and the contribution they'll make to the school and profession. The rest of the stuff can just be dealt with as it comes up.
So I'm not telling you not to seek out more information about issues, just don't get carried away with it.
Good luck!