No nukes in SA, but still significant unrest. Expect the 1983 one to be cancelled partway through (though them doing a quick finish to it later on is not out of the question), and the 1987 one delayed a year.
Strongest... depends. Kind of got a "quality v.s. quantity" thing going on between the ANZC and SAC, if that makes any sense. Time on the side of the SAC, though.
No. Mexico is far and away the strongest, which will not go away, and Canada is probably No. 2. Would also rank Victoria, Superior, Virginia, Texas, Delmarva, and Kentucky as stronger than the new US as well. Florida would run in the same range as them. Don't see the US passing anyone on that list.