GAE for Java Best Practice. How to store sorted List<string> in a most optimal way

Question

What is the best way to store lists (collections) of simple types in Google App Engine for Java?

I usually use something like that:

public class Person {
// ....     

@Persistent(serialized = "true")
 private List<Date> DatesList;

// ....
}

I am not sure how it is stored in DataStore, atomically or as a list of references? Hence wanted to get your advice on implementing these kinds of collections in a best way for performance of a query.

Like in the example above, when I load the object, will the DateList will be loaded with it. Or it will be loaded when accessed fro first time?

Does @defaultFetchGroup attribute affect this collection?

Thanks