Fruit – How long can fruit macerate in the fridge

Almost any normal sorbet recipe will contain a decent amount of sugar, and strawberries are no exception. I'd guess probably 1/2-2/3 cup per pound of strawberries. Use a substitute if you have an aversion - honey, agave, raw cane sugar, whatever you prefer. (Of course, anything liquid is going to contain some water, and cause a bit of ice, but it's still doable.) A sorbet without any extra sugar, even when frozen normally in an ice cream maker, is going to end up with a very icy texture, which will probably keep you from experiencing the flavor as much. The sugar helps soften it.

The other common way to soften a sorbet is alcohol. Rosé wine (thank you, David Lebovitz) works quite well in a strawberry sorbet. Vodka can be your go-to liquor for any impromptu sorbet with other fruits, since it'll add alcohol without any flavors that clash. Beyond that, either look for recipes, or look for mixed drinks containing the fruit you're using.

You might also be having problems simply because your strawberries aren't that great. Did you freeze them, or were they storebought? If you bought the strawberries yourself, you'd know they were decent before freezing, while not all storebought frozen fruit is as flavorful.

Finally, it's possible that your frozen strawberries collected some extra water in the form of frost, which then makes your sorbet icier. If there are obvious big chunks you could scrape them off.

The cooking technique to make the filling is basically the same as any compote or jam so I would say it would work well for most soft bodied fruit and other jam favourites.

You may have to modify the technique slightly to accommodate for fruit with higher water content to get the same spreadable texture: i.e. simmer the fruit in the sugar water until it starts to break down, strain and reserve the fruit and then either reduce the remaining liquid or only use a fraction of it and recombine with the fruit.