I know that Ground Units, especially Garrison Battalions, can be used for quelling Unrest on planets. I originally thought Ground Units contributed to the Actual Protection Level (APL) of a planet, but after a lot of forum searching, it seems I was wrong about that. So I'd like to confirm if I understand things correctly, and have some questions:
1. Above a certain population, a colony will start demanding protection, aka Requested Protection Level (RPL). How much population before they do that?
2. The Actual Protection Level (APL) of a colony is based on the sum of units with a Planetary Protection Value (PPV) based in the solar system (ships) or at the colony (PDCs). Does anything besides a ship or a PDC have a PPV, or in any other way contribute to the APL?
3. If the RPL > APL, then colonies will have Unrest. This can be reduced or quelled by Ground Units. Since Garrison Battalions (GAR) are the recommended unit for this situation, I'm assuming the Defense of the unit is what is important (since the Atk/Def of a GAR is 0/10). What is the formula for determining how much a Ground Unit will reduce the Unrest? So many points per Defense point, maybe?