Inscrs refer to boys getting frumentum publicum . Presumably the right had become hereditary by this stage. There may have been a formal residence qualification. Aug allowed Jews to avoid collecting on Sabbath. No means test.
Total figures fluctuate.
Prob only ingenui living at R on a given date. Max recorded is 320,000. 150,000 was to be a fixed number, with praetor drawing lots to replace those who died acc Suet. Aug says that in 2 BC it was about 200,000. Unclear how numbers were reduced.