Back sweetening is done to change the final taste. Use a sweetener that isn't fermentable (they are specifically made for this). When I make my wine, I stick it in the freezer after fermentation is complete to stop the yeast. You could also use potassium sorbate to accomplish the same thing. Then you can safely add sweetener without worrying about it fermenting further. If you taste it after it finishes fermenting and you like it, then don't worry about adding anything.
As far as the clarity, if you don't want add anything then time is your friend. Although if you used apple cider, the level of clarity isn't going to be very high.