what come first the cert or the training - i.e. how do you get cave trained without going into cave? or is there a lesser cert that allows entry under supervisor
It starts with training under a cave diving instructor.. Then certs.. And cave training is progressive.. It varies slightly depending on agencies but it usually is: Cavern, Intro, sometimes Apprentice, and then Full Cave.. Diver's that are interested in being the best they can be will either find a mentor or other more experienced divers to help hone their skills and gain experience in systems that are appropriate for their skill level.. After Full Cave, you have what some might consider cave specialties.. Definitely not the same as PADI specialties.. Sidemount, Adv. Sidemount (get ready to take off your tanks and push and wriggle), cave DPV, stage, etc.
IMO, the most important thing when it comes to cave / technical diving is progression.. If you skip steps in the process, or become complacent, you are setting yourself up to possibly fail in a big way..