The National Ski Patrol
has a nice introduction to patrolling. The Professional Patrol
has their own site.
I started when I was 15. Many ski areas have a "junior" patrol. Like many volunteer fire departments, you have the same training as the adults, but the work load differs. I was fortunate to be at a small area, Beacon, NY, where the juniors were told to do the same thing as the adults. If juniors were at the scene first, the adults supervised, they didn't take over.
I believe nowadays, as a "candidate", you get trained to the OEC standards before you are "official". After that, each area may expect more (EMT....).
Again, I was fortunate as an adult to be at an area, Belleayre, NY, that trains (pushes) everyone to higher their standards and work through their "Senior" rank. Courses were paid for. Many have gone on to hold officer positions, trainer positions, and earn their "National" numbers.
In addition to the regular first aid stuff, I have participated in patrolling competitions, avalance training, search/rescue training, mountain rescue....all as part of the ski patrol.
The work load, and daily training differs in each area. As suggested in the NSP site, talk to different patrols.
I have spent more than 25 years patrolling, and loved it. Now I have crossed over to instructing, but I do not regret any of the days with NSP.