FAA Regulation

Remote Pilot in Command. Commercial Balloon pilot. Designated Pilot Examiner.

No, the other people in the park are not on notice.  Yes, as long as the park is not busy enough that it would be considered an open-air assembly of human beings.

Quadcopter capturing aerial imagery for crop monitoring. UAS used for motion picture filming. Model aircraft for hobby use. 

The owner of the aircraft. The operator of the aircraft. The manufacturer of the aircraft.

Visual observer. Person manipulating the controls. Remote Pilot in Command (Remote PIC). 

Civil and public aircraft operations. Public and military operations. Civil operations. 

1 calendar month. 7 days. 14 days. 

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

100 mph 100 kts 87 mph

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