In Jurassic Park, why did Nedry do as he did?

Introduction

Tonight, me and my partner are rewatching Jurassic Park for the third time this year and we started wondering about Nedry's journey to the East Docks.

Questions

1. 
   

   Why DID Nedry turn the other safety systems off? Wouldn't simply overriding the main gate security be enough?

   
   


2. 
   

   As he hurries through the park, he loses control of the car and rams in to a road sign showing the way to the East Docks. The arrow is then turned, causing him to lose his direction.Which way should he have turned to get to the East Docks?

   
   


3. 
   

   Why did he have to go through the actual park to get to the docks? (If the answer to that is that no other route existed, is there a reason for this?)