Having been to only one event, I'm proably least qualified to answer...
1. Pin pursuit ....They hand you an 8x11 card with questions. You run around to various spots in the park, or with the one coming up in two weeks, the Poly, Contemp and Grand Floridian and give the answer to the CM. They stamp your card and you have the opportunity to pay money and buy a pin to put on the card. After all the questions have been completed, you get the completer pin for free.
2. RSP =Random Selection Process. When you sign up for the event, you tell them how many of each pin you want (0,1,2) and you tell them the order that you desire the pins. Your request is put in the computer and if the number of request is more than the number of pins, the computer decides who gets them.
3. Other secret stuff....need help on that one. There doesn't appear to be any consistency between events.