Yes, the ceremony, cocktail hour and reception will all be held at the Arts Club of Washington.
By Metro train: The Blue, Orange and Silver Lines: The Club is midway between the Foggy Bottom and Farragut West Metro Stations. Located on the same side of I Street, Farragut West Stations is only a short two-block walk (exit on 18th Street—I side). Driving I Street NW is one-way westbound. The Arts Club is located between 20th and 21st NW before the intersection of I Street NW, Pennsylvania Avenue NW and 21st Street NW. Northbound, from 20th Street NW and turn left on I Street NW. Southbound, from 21st Street NW, turn left on Pennsylvania Avenue NW, turn left on 20th Street NW and turn left on I Street NW.
If your invitation says "and guest", then yes. If not we'd prefer just you.
Cocktail attire, but wear something that you like!