The Act does not give the public a right to speak at such meetings. See Charlestown Homeowners Ass'n , Inc . If a governmental body wishes to allow members of the public to speak at its public meetings, it may adopt reasonable rules consistent with relevant provisions of law allowing them to do so. Att'y Gen. Op. As you point out in your request letter, numerous governmental bodies have allowed for public comment at their meetings, subject to rules they have developed.
Topics are usually entirely at the discretion of the speaker.
Thus, members of a governmental body could meet privately to receive information from and ask questions of their employees or of third parties, so long as they did not discuss any public business among themselves. See Dallas Morning News Co . 70th Leg., R.S., ch. Gen. Laws 2211. Therefore, there is not a meeting as defined by the Act.