Questions about the Heroes 4 map editor.

So, dear mapmakers, I have a few questions:
1 - What is the purpose of the "Player ID" script?
2 - How can I make it so that a player can start the game playing as one color (red), and after a certain event, start playing as another color (blue)? I managed to do it, but only for one day, and only if the other color (blue) is my ally, or by entering the code Nwcprometheus to open the map.