IAD pointers please.

After a bit of a gap year, sorry folks been using BA, I have used a few miles for a trip to Washington in June.
Looking forward to reacquainting myself with the Heathrow Clubhouse, but have no experience of what to expect at the other end!
I have previously arrived on internal flights at Washington National Airport which is very convenient and now feels familiar. The wealth of knowledge of you v-flyer folks never ceases to amaze me so if you could figuratively hold my had and get me from the plane to city and back again it would be a great help. In particular info on ground transportation, Lounge facilities, best way to get to the front of the queue at immigration would be helpful.
Don't want to let the side down by appearing to be a right numpty!
Looking forward to reacquainting myself with the Heathrow Clubhouse, but have no experience of what to expect at the other end!
I have previously arrived on internal flights at Washington National Airport which is very convenient and now feels familiar. The wealth of knowledge of you v-flyer folks never ceases to amaze me so if you could figuratively hold my had and get me from the plane to city and back again it would be a great help. In particular info on ground transportation, Lounge facilities, best way to get to the front of the queue at immigration would be helpful.
Don't want to let the side down by appearing to be a right numpty!
