First thing: don't listen to anything that another 0L tells you that you should know. That includes people at your school AND the number of 0Ls who will invariably post on this thread to tell you what you should have already read.
YOU DON'T NEED TO "KNOW" ANYTHING TO START LAW SCHOOL. Except knowing how to read, speak, and think critically. The school will teach you the rest. Plan to work hard the first few weeks and watch as the people who prepped before school started lose their "edge" almost immediately.
If anyone at orientation starts to tell you about how much prep they did for school, excuse yourself to the restroom, get a drink, and find someone else to talk to who isn't a gunner.