Hey copterhead,
at 18 you seem to know what you want..after ALOT of research myself heres what I know..
(First of all joining the military is an option but I guess you already knew that...Im on here to answer your question as to private companies..
Australia:
If you don't want to train as paramedic and want to go straight in as a rescue swimmer then Oz is a good option. Companys like Careflight train indivduals to become rescue swimmers and aircrewman/winch ops..but don't get me wrong, this is expensive as your training will be in a twin engine heli and only a few flying hours involved..but maybe a start! You also don't have to be paramedic, an EFR qualification is the standard I think, but has tough fitness levels. Companys like CHC, Careflight, Australian Helicopters and others on east coast is worth having a look into..
Europe:
From my research most companys in Europe hire paramedics and then train them as winchman. From what I know some military only use resuce swimmers. There are some companies who will give search and rescue training like helirescueconsult but I think this is only to private companies who have there own heli and want down the wireman/hoist training. It would be ALOT of money for yourself just to train on a EC145!!
USA:
Join the USCG/Navy & become an AST/rescue swimmer which is extremely tough. or become paramedic with years of experience and join companies as winchman..I think this is Era Helicopters policy.
From what iv learned most companies have there own policy as to hiring winchman/rescue swimmers but been a paramedic in Europe is a major +. I know the cost of training as a paramedic aint cheap but it might outweigh the cost of paying for rescue swimmer training in a helo with only a few hours under your belt and no coin left...(but the experience is good)))
Have a look at Bristow website..they hiring winchmen for down the road but paramedic is standard. It aint an easy industry to get into with limited jobs and ex mill having most of the experience, but if youv got the drive youl get there.