Last racking (a few nights ago) I did not add the Campden tablet. I was thinking to crush that and add it now. How soon after should I add the Potassium Sorbate? And then how should I go about sweetening? I was thinking to draw a bottle out of the carboy and adding some sugar and lime juice (citrus to aid in dissolving the sugar and a hint of citrus flavour) to it to get it into solution, then putting it back into the carboy for the next week or 2 before bottling. I don't want to add the sugar to water and dilute my wine any further, as I have already done that once.
I made a hard lemonade a couple of years ago. From what I recall is that I only used the potassium sorbate after fermentation and then back sweetened as I kegged.
To me your plan sounds good. You can sample and adjust the level of sweetness before bottling.