Emergency Psychiatrists tend to work in a self-contained PER/PES/CPEP/CSU (depending on where you are based) and mostly (but not always) are based in county hospitals providing care to an indigent or under-insured population. While the work may involve providing consultation to the ED, this more often falls in the province of consultation liaison psychiatry though will depend on the hospital. Emergency care for psychiatric patients is really moving away from a medical model and demphasizing medical aspects of care with more attention to meeting the needs of these patients (which is often that they are homeless, just got out of prison/jail, lack access to care/basic medical needs,do not have or do not use regular mental health services, have untreated substance use disorders, unstable social situations). It takes a certain type of personality to enjoy the work. Many people you have no hope in ever helping. Many of them do not belong there. This is why there is a move (positive imho) to get rid of/rebrand psychiatric emergency rooms into less medicalized settings for people in crisis (though with psychiatrists present). As these environments can potentially be traumatic for patients (they may be attacked or raped by other patients, they may be forcibly drugged, secluded, restrained) there is again a move to make these spaces safer and more therapeutic with less coercion. Unfortunately, this move comes at a time when the acuity of psychiatric patients is increasing, beds are decreasing. In some counties they put psychiatric patients in jail to be evaluated as they are too lazy to put funding into care for these patients.
Most of the patients will likely have a substance use problem or be intoxicated or withdrawing from drugs/alcohol. You will have to work with angry, assaultive, belligerence, aggressive patients. This is the setting you are most likely to be attacked as a psychiatrist. Not just the patients, also family member/friends etc. There will be lots of personality pathology. You may also see patients from as young as 2 right up to 100+ with a wide range of psychopathology as well as a large range of people who do not have. Your job is to keep people out of hospital, figure out who actually needs to be admitted, see as many patients as you can, as quickly as you can.
Pay will depend as always on whether it is an academic or non-academic setting and geographic locale. That is to say pay can be anywhere from 140-320k for 40hr weeks. You will get paid more if you work nights, and if you work more than 40hrs a week. Depending on the part of the country you are in (some states will only have a single hospital with a psychiatric emergency services) it is usually easy to find this kind of work as most psychiatrists dont want to.
It is not really possible to do this as clinical work full time for long without burning out or having a mental breakdown. Many people will do this for a few years, or take a few shifts for extra cash or have this as a part of their work mixed in with say private practice (outpatient) or consultation-liasion psychiatry.