I am actually a DMU grad but its been so long I don't remember. I don't think that we had an essay. Some of the faculty is the same as when I was there. If you are up to speed on current events, can put your sentences together coherently and are excited about becoming a PT then you should be fine.
Expect questions on healthcare reform, medicare direct access, ATCs and "incident to" billing, and other political things. You will probably only get one political question. The rest will probably be about your life experiences. It seems to me that there are student interviewers as well. Just be yourself.