No, even with the 2 cups of sugar per gallon it seems to make sweetend tea it still isn't super saturating the mixture. It might make it take longer to dissolve but it's not because the tea is fully saturated. They could put 4 cute per gallon and it still wouldn't be fully saturated, even when cold.
This is correct, it's sad to see that you're getting downvoted for pointing that out. People aren't seeing that It's about how rate of dissolution is affected by temperature, not saturation point. Even in the south it isn't supersaturated (although it does get very close to saturation when chilled with some brands). More would still dissolve when cold, just very, very slowly ('vigorously stirring overnight' slowly...)
Not quite. It gets close to saturation with some of the sweetest brands, but typically no. See below comment for where this confusion is coming from. Remember that rate of dissolution varies as temperature...