Be aware that there are very step sections along the wall and areas where the wall is quite deteriorated. We stayed overnight at Lao Zhao's hostel, getting to the wall and back to Beijing in one day is a bit too rush. There is 20RMB entrance required to enter the villages. Check the waypoints for access from the north side, although it might be possible to access the wall from the south we have not tried that.
The cache is peanut butter jar that holds a log book, pencil and pencil sharpener.