Soccer, having graduated from college in May myself, there are a few important things for you keep in mind
I was recently hired as a Permanent Intermittent, and at 22, I am more than thankful to be on a civil service department. Many candidates chock mistakes they made in college up to "youthful inexperience," or so a lot of them tell me. I imagine you are around my age. So remember, for people like us, any Youthful indiscretions are probably in the not so distant past...here are a few pointers.
1.Be completely honest, I can't stress that one enough! Background checks are intense (at least mine were) there is very little about you that they don't find out. You're better you telling them, than letting them find out on their own.
2.These department officials were not born yesterday, they know that guys/gals drink in college. However, if you expect to be a police officer at 22 or 23, you better be able to prove that you have a certain level of maturity that rises above the average college student. Rising to that level of maturity meant doing and not doing a lot of things...like a keg stand on the porch of the frat house...or the bar crawl (anyway you get the idea!)
I'm not trying to preach from on high, because everyone has had their indiscretions, myself included. I have, however, known what my career goals were for a long time and have lived accordingly....luckily it paid off. The department obviously has an interest in you, otherwise they would have just tossed you to the curb, so don't be that upset...but remember college wasn't that long ago!