What do they do? Serve warrants? Surprise people with drug tests? They don't appear to be prepared to handle dangerous situations, so are they accompanied by local police?

They do not serve warrants, they may pick up someone for a probation violation, ( you would call it arrest although it is not really an arrest)

But they do home inspections, they do inspections of work places, check to see if you live where you say, do field drug tests.

And their job by and large are not all that dangerous, but they are POST certified Law Enforcement Officers and most are armed.