The W&OD and Custis trails are horribly signed. As you approach Falls Church, the WO&D branches off to the left. Arlington County has some bike maps that should help:

<http://www.co.arlington.va.us/Departments/EnvironmentalServices/dot/planning/bike/EnvironmentalServicesBikemap.aspx>

There is a hill on Walter Reed Drive, starting on Four Mile Run, that ought5 to provide some sort of training. It was a memorable part of my morning commute for a while.

Paul