Not sure which yeast you used, but I have used Nottingham in the past. It ferments out with a clean taste and very dry (Final gravity was less than 1.00).
For carbonation, use the same amounts of priming sugar as you would for beer (1 oz per gallon).
As far as back-sweetening, the easy way would probably be to use an artificial sweetener like Splenda or Stevia. Option 2 is to pasteurize and I believe there are threads on HBT on how to do this. If you choose to pasteurize, I do recommend the stove top method. We tried pasteurizing in the dishwasher, which resulted in some bottle bombs and a broken dishwasher :cross: