You are welcome. The general area you are staying in is relatively flat; there are some hills in the areas around Georgetown and the National Cathedral (hence, my earlier suggestion to use the hop-on/off trolley tour). We used a combination of walking, buses/metro (subway), and Uber to get around this past weekend. Taxis are also plentiful. I never rent a car when I am visiting DC.

The Mid-Atlantic Forum is a good place to find general information for first-time visitors:

http://www.flyertalk.com/forum/mid-atlantic-453/