Are you going to be shooting with permission or as something more akin to grabbing within a public performance? Are the images for sale to troupe members or for your own enjoyment? Will it always be in the same theatre of different theatres? Will you be shooting within live performances or during rehearsals? The answers to these question will decide what you can and, more to the point, what you cannot do. Rehearsals can be a great time to obtain 'publicity and performer shots', action will stop and you may have the chance to see the same moves performed several times and select the best location, time, angle, etc. You have some very good advice about lens capability and shutter speed, I would not rule out the use of flash if the shooting situation will allow, e.g. not a public performance! However, getting it right can be a challenge, especially with multiple flash sources to avoid killing the lighting 'design'! I suggest that learning what works for you will be the essential first step, we all see things our own way. The same leaping dancer can be shot many different ways, none of them are wrong yet only some will appeal to you. You will need to establish your own style. When starting, and within the confines of how you have to work; - always try to 'over shoot' the situation. Do not die waiting for the perfect shot, (a) make it happen by studying the flow of the act, (b) capture all of its variations, you can always discard the failures later but can never capture the shots you have missed. Try to enjoy what you do, it will help you to capture what you want.