Try this plain or with vanilla first. That will gve you a good sense of the tart-sweet play-off and you can then better decide (and tweak) flavorings, additions or the sweetness of the base.
Yes, you can use low fat or nonfat yogurt but I highly recommend going with whole milk yogurt first, either yogurt you make yourself or store bought. In any case, if using store bought, avoid those with thickeners like pectin and carrageenan, especially common among the low- and non-fat versions. One doesn't get as good a drain from yogurt that has thickeners in it.
Start with 6 cups whole yogurt. Line a colander or large sieve with several layers of cheesecloth and place over a large bowl. Add the yogurt to the colander then fold the excess cheesecloth over the top of the yogurt. Refrigerate and allow to drain for at least 6 hours.
Scoop the drained yogurt into a bowl then stir in 2/3-3/4 c sugar (I prefer the slightly lesser amount of 2/3) and 1 t vanilla extract (homemade or store bought), optional (I like unflavored but simply sweetened frozen yogurt and vanilla flavored; try it both ways). I use very fine white sugar for this. (It's also called 'superfine', 'castor' and 'baking' sugar and is more finely grained so that it easily dissolves. Standard-grain white sugar is fine and is used in the same amount. It just takes a little longer to dissolve.)
Stir the mix till the sugar is completely dissolved. Place the bowl in the fridge for 1 hour, then freeze according to the directions of your ice cream maker.