They send a car to your hotel to pick you up. You have to contact Belmond (or Viator) to arrange. There is an extended option where you can stay in the Belmond or another hotel (in Aqua Caliente) and return to Urubamba later.

Yes, is all included.

You won't find an agenda, but it's pretty simple. The ride to Machu Picchu from Cusco is about 3.5 hours. Food is excellent, but get into the observatory car for viewing ride into the mountains. You won't see anything on the return because it is dark. On arrival, a bumpy 20 minute bus ride up the mountain to the actual site. The walking tour is a bit strenuous with many stairs, but worth it. The tour guides will give options for people who want to go up higher, whilst others could take a simpler walking path. Don't come all this way and stay in the lodge outside the site. Take the less strenuous path. It's worth it. After the tour (about 2 hours), you can have a snack and coffee in the lodge. It's a nice breather before going back down to the train. The train ride back features an outstanding gourmet dinner, and the wine flows. Yes, its pricey, but it's the only way to see Machu Picchu.

I think there is pick up from several Cusco hotels. I am not sure what ypu mean by a bi-modal tour, but my impression is the tour runs rain or shine.

very sorry have only just seen question. Yes you can go one way only. That is exactly what I did. But I stayed in Ollantaytambo. good luck. I was unable to book outbound trip online but managed to do it on arrival in Cusco.