I know what XML is, and Ive seen many examples but I have a few conceptual questions about sharing info with it.

Suppose we have this example: A database say its Oracle - has some data in it according to a schema. If one wants to move that data - to say a MySql database, Im told that the data can be put into an XML file. But does that XML file need to have the schema encoded in it? If not, how does the receiving system know how that data is organized? If the file needs to have the schema encoded in it, how does the destination DBMS understand and create the database properly to be able to store the data?

In generalis the organization of the info (tag names, nested sections, order of information, etc) in an XML file specific to the two applications sharing the information? Are there a set of standards that set the organization of files sharing certain types of info?