Recently finished riding from DC to Pittsburgh on C&O/GAP and it appears most of the pumps are open and operational along the trail. I think we only used one during our trip. As for trains, you do hear a lot of them near the trail. We stayed in motels and one AirBnB in Confluence. Lots of trains in Cumberland but we had done a 90 mile day so the noise didn't bother me plus we were on the 5th floor so somewhat above it all. The AirBnB in Confluence was closer to the tracks and, as we were preparing to leave, I commented that I only heard two trains during the night. My riding partner said there were a lot more than two trains during the night. Enjoy the ride, we had a great time.