The 2+ is meant to cover the extra terrain to be added split evenly. The suggestion is to have 8+ pieces set aside - so if you have 16 pieces set aside instead, you'd set out 4 each round instead of just 2. The 2 is meant as a minimum point.
As for the change to the Force Org - the idea is to have a larger number of units rather than simply larger army crushers involved. A small change to make one consider new approaches to armies that you're already familiar with, just played in a slightly different way to bring new life into them.
