A: RONR does not speak specifically about school board meetings. It's likely that your state, community, or school district may regulate their procedings.

As far as boards in general, RONR states that board meetings are held in executive session, and that non-members may be invited to attend and to speak. It is up to the board (not its chairman) to determine how long a guest may speak. The conversations by board members to the guests are unrestricted. But, again, check your other authorities for procedural rules. RONR is superceded by them.