Photo Credit: russ
The Majestic theater is located in the heart of the Theater District in Manhattan, at 247 West 44th Street. This is between Broadway and 8th Ave. It is within a short walking distance of a few subway stops.
The theater itself was built in 1927 and has a seating capacity of 1655 people. There is a box office there as well, where tickets can be purchased (phone: US Country code 800-677-1164). Tickets cost anywhere between $20 and around $150. Matinee shows are cheaper, however there are a select number of $20 tickets even for the evening shows in the back few rows. All seats have at least a decent view, however if you want to get the full experience (and see actors/actresses faces), spend the extra money for first level seating.
There seems to be no dress code for going to these shows, however it is typical to be less formal for matinee showings. People tend to be a little more formal at evening shows, and of course looking nice is recommended, and why not? You're in New York. If you are looking for the bare minimum, there doesn't seem to be any, as people were recently seen wearing jeans, sneakers, and even ripped tshirts to evening shows.
Note that this has only been confirmed for the Majestic Theater, you may want to check your specific theater.