FAA Regulation

does not contain any exposed rotating parts that would lacerate human skins upon impact. has an airworthiness certificate issued under Part 21.  is labeled as Category 4.

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. 

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

Only when visual observers participate in the operation. Alone, if operating during daylight hours. Under the direct supervision of a Remote PIC.  

The FAA does not allow the use of ADSB-out for sUAS. Anytime you are flying in controlled airspace. Only when flying in a Temporary Flight Restriction.

Name and Phone Number of the Operator. Address and phone number of the pilot. Location and altitude of the controller.

September 30th, two years from this year.  October 25th, one year from this year. October 31st, two years from this year.

0.55 pounds or less.  0.75 pounds or less. 0.65 pounds or less.

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.

Visual observer.  Person manipulating the controls. Remote PIC.