What two files are typically (this is kept generally) included when developing a content type, and what is the purpose of each?

There is generally the main content type file that holds things like the content type ID, name, group, description, and version. There is also the ContentType.Fields file which contains the fields to include in the content type that has the ID, Type, Name, DisplayName, StaticName, Hidden, Required, and Sealed elements. They are related by the FieldRefs element in the main content type file.