Chins regularly eat their poo. The poo they eat are actually a different consistency from the normal poos they leave in their cage though. These "edible poos" are called cecotropes and are formed in the chinchilla's cecum (a little pouch in the intestines which contains friendly bacteria to break down fibrous foods and extract extra nutrients from it). These cecotropes are soft, smaller than regular poos, and tend to be clustered together. They are rich in nutrients and also contain some of the beneficial bacteria which lives in the intestinal tract. Healthy chinchillas will eat their cecotropes. I would be concerned if a chinchilla was not eating their cecotropes... the only time I've found cecotropes in the cage (uneaten) were in rescue chins who were stressed, unhealthy, and fed a poor diet. It is completely natural and important for the health of a chinchilla.
As for your second question, many chins twitch or make noises when they sleep. She is probably dreaming or they are just involuntary muscle twitches... it happens to me too sometimes when I sleep, lol. Sometimes it even wakes me up!
