Whether 1. is allowed depends on the specific requirements of the organizer. Some performances are ok, others are not (or you need a press card to bring them). Suggest telephone consultation. Of course, even in many performances where cameras are not allowed, many people can successfully get away with it.

2. If you want to bring it, it is recommended to consider a monopod. The seating space in the gymnasium is relatively compact. Unless you buy some tickets for special seats, tripods are generally difficult to move. Of course, you can also prepare a tripod, and you can remove one foot separately for use. After all, tripods are much more stable when they are used.

Another tip: If the light is dim, consider using high sensitivity, but don't turn on the flash. It is useless to turn on the flash (the distance is beyond the effective range of the flash, unless you want to shoot the back of the head in the front row), and it may also interfere with the performance or other audience.