No, the number of Personal Responders is set by the subscription plan and cannot be exceeded. Users can choose a plan with a higher number of Personal Responders if they wish to have more people available to respond in case of an emergency.
Background service, when turned on, means the Iyzil app keeps running in the background. You can easily trigger the Panic Alarm without opening the app (by pressing the Volume button three times or Shaking the phone).