A. Avram et alii, in Revue Archéologique 2013, publishes a bunch of sling bullets from the Dobrudja (Rumania). They're the normal type (about 3 cm long, a bit less than 40g). They give names of "King Alexander" (= the Great), "Alexander the general", and the names of unit commanders,

Avram also gives an excellent catalogue, with dates, of all names known from Greek sling bullets (from ca. 400 to 133 BCE), and a list of all battles / sieges where sling bullets are known archaeologically (from 373 BCE to 86 BCE).

It's very good indeed, the best thing I've read on the topic.

Yes, they play an important part in many operations, sieges but also river crossings and the like (along with the Macedonian archers)