I think it will all depend on what type of final product you are looking for. You had mentioned you wanted a more sweet carbonated cider, so I would probably consider the pasteurization sticky at the top of the cider forum. This seems to be the only method of getting sweet/carb'd without kegging and force carbing.
My personal opinion is to add sugar until you reach a specific gravity of 1.050 or so. This will leave you with more of a cider instead of treading into wine territory. (OG around 1.070?) This is just what I do, not set in stone.
CvilleKevin has a LOT of great info in his sticky thread.
http://www.homebrewtalk.com/f32/results-juice-yeast-sugar-experiments-83060/
I don't use nutrient and go the raisin route. The theory is that it adds some tannins and some snacks for the yeasties. Since I use raisins, I haven't used the concentrate. I probably need to try that since some have said it adds complexity to store juice.