When I worked in the peds ER, these were my duties:
Child protection- forensic interviews with children and adolescents brought in for suspected physical or sexual abuse or neglect. At my hospital, when a case like this hit the door, it was immediately sent to social work, who would then give recommendations to the medical team based on the interview (ie, internal pelvic vs external, rape kit, etc). This included taking pictures of any visible injuries and coordinating with state child protection services and law enforcement as appropriate. These cases may also entail testifying in court about the interview that was done.
Crisis intervention/Trauma: Our pager went off to each Trauma STAT, Major, and Minor. We were the liaison between the medical team and the family, including chaperoning the family into the trauma room to observe if they would like to go in (and are emotionally capable of dealing with seeing that). Lots of crisis counseling, support to families, assessment of whether the trauma resulted from child abuse or neglect and addressing that as appropriate. There is mandatory reporting to the police for gunshot wounds in my state, so that was our job.
Deaths: We were present for every death, and had some assistance from the chaplains. Crisis counseling for the family, crowd control because inevitably 30+ people are going to arrive at the hospital, clipping a hair sample for the family to keep, plaster molds of hand/footprints, photographs of the family holding the child one last time, calling the Medical Examiner's office, assisting in initiating funeral arrangements.
Ingestions: Any kid who ate or drank something they shouldn't have got a full assessment, especially if they're in the under-5 crowd. Lots of family education to parents on locking up their medications and household chemicals so the kids can't reach them. Exceptions might be a drunk teen who's just sobering up and will go home.. And ODs as a suicide attempt we'd tell the ER to call psych first and intervene only if needed.
Burns: If they were suspicious, they got a consult. If they weren't, we didn't get called. Suspicious would include the pattern of the burn not matching the proposed mechanism- ie spills get everywhere, so it would be highly unusual to hear "spill" and just see one blister. Like to get pics of these, too- b/c burns and bruises go away and it's nice to have on record.
Other: SW determines if any patients require visitor restriction, are used to assist with disruptive family members, can assist with housing, prescription, transportation, or meal assistance as appropriate, and provide supportive counseling to patients and families as needed.
In the adult ER, I'd include lots and lots of domestic violence counseling/referring and nursing home placement issues. Again, they'd be reporting the GSWs (they get a lot more) and working with the trauma patients.
Teaching hospitals often have psychiatry residents on-call in the ER so social work does not get as involved in that. Community hospitals are more likely to utilize masters-level social workers and counselors to do behavioral health intake and contact the on-call attending psychiatrist to determine the treatment plan (admit, day treatment, refer out, etc).
As far as texts, etc, I can't think of anythin off the top of my head. However, I believe that most ER social workers have gone through health concentrations while getting their MSW. Oh and yes- unless you're in a really rural hospital, hospitals generally require you to have your masters.
