this site should help answer many of your questions: http://tinyurl.com/32su22c
I don't think there is anyone with less then 15+ years bid onto the rescues, as its the best gig in the city, but you can get detailed or take OT on them. On any kind of major rescue call though, the ambulance crews will helping the rescue with tasks since its only staffed with two. Everyone is similarly qualified in rescue skills after hire... but, competence in them is another thing.
As far as pay, there are plenty of opportunities for OT. If you pick up a special event detail (Steelers/Pirates/Pens games, concerts, fairs, etc), you make something like 35/hr, regardless of seniority or base rate. You'll also make acting crew chief pay on occasion. But believe it or not, the starting rate is livable for here. Pittsburgh is a very cheap city to live decently in. Besides, you're going to be at work all the time. Ha.