1. Unanimous between the remaining active players. Note that a country in CD is not active so is not needed and will not be included in the draw. But also note that a country in CD can come out of CD when you aren't expecting it and end up in a draw. Also note that a country with 0 supply centers, but in the fall retreat or build/disband phase is not yet eliminated so would be included in any draw. Have to wait until Spring for those players to be eliminated and therefore not part of a draw.

2. Unanimous required, yes. Done by a Mod, not typically. Sometimes they might force pause a tournament game or other special game within the special rules of those games, but I'd of course have to defer to them for what their current policies are. It is usually best to make it clear in global chat the period that you need a pause for. If another player doesn't come back, then after some time, you might be able to get a mod to unpause the game. But note, you should NOT join a game knowing you'll need to pause in the near future, at least not without discussing it with the other people in the game ahead of time. And don't expect that a pause will be granted just because you ask for it, except in special cases such as tournament games where the tournament rules apply.

3. Yes. So it doesn't go on anyone's record. Personally, if a game starts and one player doesn't show up and so everyone wants to stop the game, I'd rather draw to split that person's points as punishment to them, than cancel it. But other people would prefer to cancel so they don't get an unearned draw on their record as a matter of integrity.