For peach bellinis, should I add lemon juice to the purée? Is the sugar/liquor necessary? & do I need to strain and freeze the purée before using? And can I use sparkling wine instead of prosecco?
First off, Bellinis are always peach. If you use another flavor, the drink gets another name. You can use other sparkling wine than Prosecco, but before you commit to that, I'd suggest you try them side by side both ways. Prosecco has a unique texture because it is not made in the "traditional" way. Now for lemon juice.... I'd think using it would depend on the flavor of the peaches. Altho I always like it in my peach ice cream because it intensifies the flavor of the peaches. You know, makes them even more peachy? Yes you need to strain the purée so your Bellinis won't be lumpy. And you don't need to freeze it, but it should be super cold so your drink will stay cold.
You could use any kind of sparkling wine. The need for lemon juice depends on the acidity in the wine--taste and see if you think lemon juice will add to the flavor. I don't strain mine, but I suppose if you want to be a bit more elegant, it wouldn't hurt.