If you are staying in one of the hotels in our block, the venue is walkable (there probably isn't another option because it's so close - unless you bribe someone who works for the area to let you ride in their golf cart).
No official dress code. But! We're in DC for a night out - might as well put on something nice to celebrate with your family and friends.
The itinerary includes the activities for the week - it's a great reference so people can remember the time of the wedding and reception. It also includes the rehearsal details, as well as details for the private monuments tour. The monuments tour is for the wedding party and immediate families. When you RSVP, you will have the opportunity to RSVP for all of the events for which you're included.