You will need to have as many of the prerequisites as you can to be competitive. The required ones are English, A&P, and chemistry or micro. There are others that are supposed to be completed as well, but are not required to start the program such as PHI. You need your CPR certification before school starts.
As far as the information session, I would call. I don't think they REALLY keep track of that if you want to know the truth. I did mine 2 years before I applied, and I SERIOUSLY doubt they have proof of my attendance.
The most important thing is the prerequisites, and the Hesi A pre-nursing exam. If you score well on those, they will admit you. The trick is they must be complete before you apply.