You don't mention who is hosting the track day, but whatever group it is should provide you with information like that posted at
http://www.porschenet.com/DEtech.html . If nothing else, they will likely have some form of helmet requirement and should have some basic equipment requirements (tread depth, etc.). My local Porsche club requires an inspection in advance of the event to cover the items on the list at that URL..
Track days are a blast, have a great time and stay safe!