You are on your own for food. In many cases local organizations sponsor meals, but you are free to choose between them and nearby restaurants. The campsites are situated so that food is close at hand. These are demanding rides.
Age is no barrier, lack of training is.
You can't skip the training and expect to fully enjoy these tours. During the day there will be two support vehicles patrolling, but you should have the knowledge and equipment to fix flats and make minor repairs.