Oracle Database Discussions

Could someone tell me the advantage of Materialized view on prebuilt table?. I'm unable to understand the concept from the Oracle documentation. I need to know the answers for following questions.

1) Is the data stored in table and MV same?. Does the query retrive data from table or MV?. The query internally uses either table or a view as the names of both are same.

2) Our DSS application is generating complicated queries and executing for long time. Is there any way I can optimize those queries using MV without rewriting the code in the application.