O78,
Since you are specifically interested in the 412, there are a number around the country, mostly primary tasked for Ambulance or Medevac, but SAR when tasked.
CHC have Helimed 1 at LaTrobe Valley, Victoria, and HEMS 3 out of Bendigo, Victoria, both extremely professional and highly regarded units. IIRC, using 412EP's.
CareFlight operate a 412 out of Sydney, and featured (along with Helimed 1) in the Sydney - Hobart yacht race rescue a couple of years ago.
Queensland Rescue have 2 412's, one based at Archerfield, Brisbane, and the other (IIRC) at Townsville. Once again, highly competent and well respected operation.
Most 412's have a heap of gear in the back, at least one Ferno 50 stretcher base athwartships, two paramedic seats, some also have a FLIR control position, also external winch, and the ability to load a collapsible stretcher fore and aft on the stbd side when needed.
Tasking for Ambulance work in Victoria comes from the state run Air Ambulance, onshore (overland ) SAR is initially a State Police responsibility (unless an aircraft is involved), and they will nearly always task their own assets, either an AS350 or a 365N2 Dauphin. They also operate a 365 N2 for the Air Ambulance, covering Melbourne. Overwater SAR tasking is the reponsibility of AUSSAR.
Life wasn't meant to be easy........