>>3337554There can't be any recommended focal length. It's up to how close you can get or can move, how much DOF you want, and so and so.
Manual focus works allright, or go Tv mode (but you will have some trouble with moving lights who will fuck up your exposure). Use the center AF point only, as this is the most sensitive.
No need to sneak your camera. A lot of people today record with their smartphone anyway.
Important advice : don't hesitate to use ISO3200 and 1/200 sec. Grainy is better than blurry.
