1. Sort of, yes. The acids wouldn't have had a chance to mellow and smooth out.
2. That probably the best time. Make sure it is stable so that the yeast don't eat the new sugar added, releasing more CO2 and causing your bottles to explode. Terry Garey's book does suggest that you can also sweeten it when serving as another time.
3. Garey's book suggests...
1 gallon of water
6-8 lbs of raisins (depending on how much alcohol you want at the end)
3 tsp acid blend
1 tsp yeast nutrient
Flor sherry or Montrachet yeast
I would then probably add 3 cinnamon sticks, but others should weigh in on that.
I wouldn't use water jugs. Plastics give off flavors, and they are hard to keep clean, especially along the seams. However, a good plastic primary fermentation bucket is good to have around, and then transfer to a glass secondary.