They do not respond to jobs unless they are requested to by the precinct police officers on the scene. Since all ESU officers are also qualified and licensed Emergency Medical Technicians (EMT), they do get advised by dispatch about any medical calls in the patrol area in case they are nearby, particularly any jobs identified as having a person with difficulty breathing. read more
Those ESU guys do a lot of the stuff traditionally done by Fire and Rescue crews, hence all the equipment. Ad to that they are entry and SWAT guys , also. I believe NYPD has 10 of those trucks rolling around the city.. read more
Probably train and exercise. Most special service branches like that train every day so they can be ready to go when they get activated. I'm pretty sure NYPD ESU works multiple squads so they probably rotate days and shifts to help with the workload. read more