Town Hall

Address: 123 W 43rd St, New York, NY 10036, USA

There is limited street parking in the area, but there is a parking garage right across the street at Myers Parking Garage located at 141 W. 43rd St. There are many other garages in the area because it's Times Square/The Theater District.
The area is also very easily accessed by public transportation:
By Subway: 1, 2, 3 - Times Square-42nd Street (7th Ave.-Broadway); A, C, E - 42nd Street-Port Authority (8th Avenue); B, D, M, F - 42nd Street-Brant Park (6th Avenue); N, Q, R - Times Square-42nd Street (Broadway); 7 & S - Times Square-42nd Street (Broadway-7th Avenue)
By Bus: M42 runs the length of 42nd Street from East to West; M5 & M7 buses run North along 6th Avenue/Avenue of the Americas; M5 & M20 buses run South along 7th Avenue

Town Hall has a mezzanine which is accessed by stairs, however they apparently have an elevator - that is only operated by a member of staff.

"The theater is wheelchair and visually-impaired accessible. There is a section available for wheelchairs in the left rear Orchestra behind row S. Along with row E, the front right side Orchestra has seating for the visually-impaired. Wheelchair, visually-impaired and companion tickets are available on Ticketmaster by selecting 'Accessible Seat Options' and can also be reserved at the Box Office. Anyone with accessible seats and those requiring infrared hearing devices should ask to speak to the House Manager once inside the theater for accommodations."

There is a balcony, its mainly accessed by stairs, but there is an elevator available.

Yes. "Anyone with accessible seats and those requiring infrared hearing devices should ask to speak to the House Manager once inside the theater for accommodations."
The show I went to had two ASL interpreters who were featured permanently in a spotlight, who signed the entire show for deaf/hard of hearing fans.

The restrooms are on the second floor.