I greatly enjoyed my job, I was a paramedic from '87 till '00; it both took a lot out of me and gave a lot in return. I would not have changed the jobs I had, or the choices I made.... lots of interesting experiences.
I recommend you talk with medics and firefighters to get a feel for as many opinions on this as possible. Also, I believe that experience in an emergency room is invaluable. There are often volunteer positions that are available in an ER.
As far as qualities, a sincere desire to help others would be at or at least near the top of my list. Everything else can probably be taught/ learned both in the classroom and on the street, but without this quality, I don't think a person can be effective in this career. This quality should, In my opinion, be emphasized in any application process as well.
Feel free to drop me a private message if you like...
Tim Hogan, Edmonds, WA, USA
(former paramedic & currently a firefighter)