Music Hall of Williamsburg
There is only street parking.
If you arrive before doors and alert security, they will usually allow you in the venue first.
The main entrance for the venue that they direct fans in through has stairs to every level. If you speak to security they will let you in the door they use for the exit/smoking section which is flat. There is an elevator that brings you to every level of the venue (basement lounge - this is where the only restrooms are), the merch area/bar, the main floor, the balcony/bar.
There is no designated area for accessible seating. However, they will allow you into the venue first to get to the balcony if you request it before doors. The view is great from the balcony, though sometimes for sold out shows it gets very crowded in the balcony, and other people don't care that they're crowding you or are in your way.
Yes, there is a balcony, it can be reached by stairs and elevators. There's limited seating (chairs paired with tables) and also bleacher style risers in the back of the balcony for sitting or standing on. There's also a bar and small lounge area in the balcony.
"I have only received a seat when I requested it before doors. After doors open if I arrive, they have never helped me find somewhere to sit in the balcony which means I usually cannot see, or have to stand."
There's only one restroom and they're in the basement. They can be reached by stairs or elevator.
Their website says: "Do you have ADA accommodations? Yes, when getting to the venue (we suggest trying to arrive before doors open—door times are listed on each event page), please alert security, who will make sure you are taken care of. If you have additional questions in advance of your visit, please contact email@example.com."