FAA Regulation

is required to receive ATC authorization.  must use a visual observer. is required to file a flight plan.

ensure that the human beings who are not participating in the operation are under a covered structure or inside a non-moving vehicle. ensure the sUAS is equipped with a parachute make sure the area is closed or restricted-access.

Compliant with Part 107. Part 107 does not apply to this scenario. Not compliant with Part 107. 

Turn down the intensity of the light.  Look down at your controller screen to fly the drone and find the obstacle. Turn off the strobe light.

No, 14 CFR Part 107 only applies to sUAS weighing less than 0.55 lbs. Yes, there is no lower weight limit for operating under 14 CFR Part 107.   No, roof ...

No more than three as long as the Remote PIC maintains visual line of sight. As many as he/she can handle. No more than one. 

With the controlling agency’s authorization.   Regulations do not allow this. When flying on airways with an ATC clearance.

Continue the mission, airplanes are not allowed to fly lower than 500 feet AGL unless around an airport. Give way and stay clear from the crop duster.   Continue the mission, ...

If prior permission is received from the Federal Aviation Administration. If precautions are taken to avoid injury or damage to persons or property on the surface.  Only in an emergency.

Over suburban areas. Over a parade or other social events. Over a sparsely populated area.