I couldn't say about the first aid training, but once the Nemesis train has left the lift, there's no stopping it until it hits the brake run... as in, there's no magic 'e-stop' button that stops it in its tracks. It's all at the mercy of gravity and 'free-falling'. So they wouldn't have been able to get you off the ride until you'd hit the brake run at the end. :)
All and well but what happens if something happens to someone in the que or around the station? My guess is that one or 2 ops are probably trained for first aid.