We didn't camp b/c we do day hikes. This spring (actually hopefully in a few weeks) we'll do a few one-nighters. I'll make sure and let you know how it goes. From what I understand, the lean-tos are usually pretty busy during the peak hiking season, so it seems it is rare to be the only person at a site. That kind of leads into question 3. I think I'd feel safer hiking alone on the AT than I would other places b/c of the other people. We also hike in the Adirondacks a lot and I wouldn't hike there alone, just because it is so remote. However, I would hike the AT alone, I think
The demanding-ness varies a lot. We did one day hike (to the summit of Greylock) that was about 12 miles. We gained about 1200 ft in the first mile or so. THAT was hard. It took us about 6 hours to do those 12 miles. Another day we did an almost totally flat section and covered about 15 miles in 5 hours... so it totally depends on the terrain you are covering. I don't know much about the WV section, so I have no idea about how hard it would be. The trail is very easy to follow, well marked, etc though. Having hiked in the ADKs a lot, there is a bit of "mental" stress that takes a toll when you aren't quite sure if you've lost the trail. I think you wouldn't have to worry about that much on the AT.