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

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.

The Remote Pilot in Command (RPIC). The owner of the aircraft. The FAA.

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.

Yes, my category 2 sUAS is approved for sustained flights over people. Yes, as long as you are transiting.  No, you must wait for the traffic to stop before you can ...