1. Special Rules Game. It is the term used for game boards which are being used for something that isn't Diplomacy.
2. This is to make it clear who you can/cannot communicate with, while keeping your Tribe's public chat hidden from other tribes. Game Boards are for communication with other individuals in your Tribe, the QuickTopic threads are for communication visible to all other members of your Tribe.
3. There are initially 3 game boards, then those are cancelled and two new game boards are set up at the first Tribal Merge, then those are cancelled and one last one is set up at the second Tribal Merge. Therefore, there are six boarda total, but only a number equal to the current number of Tribes will be in play at any one time.
4. It's 'More than 2' so in your scenario both yourself and bo_sox would have immunity unless someone else also played an idol.
Answering your question though, if more than 2 idols are played, *all* have no effect, regardless of the order they were played in.
5. Thanks for reminding me, I need to take that out. The mod team denied permission to use the dummy accounts, so eliminated players will stay on the game boards until they are cancelled, you just will not be allowed to communicate with them.