There is always a pretty good demand for technicians these days. Keep in mind that cars and trucks are becoming more and more advanced and complex. The "average technician" is slowly fading. Most techs these days require many different areas of skill and knowledge.
Techs at the dealership I work at make anywhere from ~50K a year up to ~120K a year. It all depends on how skilled and experienced you are, how willing you are to bust azz, organizational skills, etc etc.
Dangers: There's always danger when working with anything mechanical and with chemicals. Job safety is always something that techs must follow religiously. Otherwise there is always the risk of major injury (or even death) if precautions aren't taken. Thats with many jobs out there though. I'd say as long as you are safe, the risk as a tech is rather low.
Benefits?: hmmm Ya got me on that one. Benefits are going to vary depending on where you work. ie: dealership, city or state job, independent shop, etc. At the dealership I work for we get 5 or 6 paid holidays per year, 2 weeks vacation (after 2 yrs employment), and well.... thats about it.
Hope that helped you some.