I second jeanne's reply. The local munches and sometimes dungeons organize classes once or more a month on various BDSM techniques (like jeanne mentioned at the Lab), and there are also conventions which usually have panels on said techniques. As for more personal training, some Dom/mes that I know have mentored to gain the skills that they have now. This was done through friends and new contacts met from munches and local dungeons. However, it is safest to get plugged into your local community first and go from there...

As for your questions, all of my experience in "training" has been in person. Our local munch's class is free and lasts a few hours. Dungeon demonstrations last around an hour or less depending on the complexity of the skill and cost $20 member cover to get into the dungeon. Panels and seminars last around an hour and the cost is usually part of an overall fee for the entire convention/weekend seminars (usually $30-45/day to $150 for con run). I have been to demonstrations on flogging, violet wands, and suspension. I have attended panels on bondage, DM monitoring, and play partner guidelines for scenes. I am being currently mentored off/on in wax play, communicative and observational techniques, bondage, and flog making. And for clarification, although I am a submissive to my Master, He is training me to eventually be able to Top at His command (with consent of all present of course) so that He may Dom me in return.