My specialization is low-light and location photography, and my personal passion is "band photography", i.e. photographing musical or dance performances in available light, which often involves special effects stage lighting, strobes and lasers as the only light sources. I would like to share some of my thoughts:

1. You will not be able to use your flash to much advantage - at 9 meters, this flash won't have useful throw.
2. Also, the flash would be distracting to the performers: Most performances frown upon, or outright forbid, use of flash.
3. Shoot short bursts (4-6 frames each) in the fastest burst mode your camera supports, starting just before an interesting movement if you can predict it. Often one or more frames of the burst will catch a perfect frame. Also, merging the best frame with full opacity, and the two frames immediately surrounding it at 50% or lower, unequal opacity often results a very dynamic, high-impact, even startling image... as long as this technique is not overused. Flaws in the individual images of that set fade to insignificance.
4. When using burst mode, if you are using AF, set it to AI or predictive AF or Smart AF mode if you have that option.
5. Pre-focus whenever you can: Set your zoom to a framing you would like, then lock the zoom ring if you have that option, then in manual focus mode, focus around midway along the distance range of movement of the performers. That way, your camera wastes no time in autofocus hunting, and you get quicker shutter response.
6. Pre-set exposure if you're comfortable with that: Use manual exposure mode, and set your shutter speed to what the spot-metering indicates as appropriate for the performer, ignoring the background. That way, neither will your camera's processor waste time metering, nor will you get widely under or over exposed frames due to instantaneous metering of either a dark background or some momentary bright spot.
7. Avoid having any of the stage lights anywhere in your frame, if at all possible. If unavoidable, try to keep such lights in the diagonally opposite quadrant of your frame, from the persons of interest.
8. Clean your lens front element, and if necessary your rear element if dirty, very very carefully in advance. In a high contrast low light environment, even the slightest smudging on your lens will show horrid blooming of bright areas, and light-cloud effects, besides reducing your image contrast and clarity.
9. Shoot a mix of high-ISO and medium-ISO images. The high ISO ones might be sharp yet noisy but will "get the shot" more often, while the lower ISO ones might have motion blur, but look cleaner and more representative of the performance.
10. I personally don't bother with my wide angle lenses in situations like you describe: At 9 meters away, the wide will make the performance area pretty small in the overall frame. I stick to teles, and more often than not, I'm zoomed all the way to 500mm, to capture interesting detail which the point-and-shooters will never get! Yes, all this while hand-holding my Bigma, so the arms ache pretty badly the next day.
11. Expressions, and perspiration, are two areas I concentrate on, as they bring across the effort and the humanity of a performance more than anything else.
12. Spotlight reflections on accessories or jewelry worn by performers: Another picture idea that has worked for me.

These are just one person's views, so it's perfectly possible that doing exactly the opposite of these suggestions might generate an interesting image or collection, or result in a distinctive style all your own. Just don't forget to enjoy the performance for yourself, too.