Aloha Rodney,

r> On this topic, wouldn't the fact that 1) the suttas were composed
r> in metrical form (which unfortunately is lost in translation and 2)
r> the suttas were -in the beginning- not "read" but orally
r> transmitted by bhanakas indicate that the Dharma was - to some
r> extent -"chanted" or "sung" ?

1) Suttas were composed in both prose and verse.

2) As I understand, The passage in question talks about the regular recitation of
Vinaya during Uposatha or other acts of Sangha.

There was nothing to read from, so naturally suttas were transmitted
by declamation. It is not singing.

Mahalo and malama,
Dimitry