SQL & PL/SQL

Hi,
I am using ORACLE 11gR2 and LINUX 5.

I want a query which will give me output as :- The sql/plsql query which is consuming most resources or else which is taking the most time to execute. Also if i can specify time in query then can it give me that in this particular time how many times a same query got executed ???

For an Example : -
My query should be like .....

SELECT <MACHINE_NAME>,<OS_USERNAME>,<SQL_FULLTEXT>,<columns specifying the recources used by SQL>,
<how many times the sql got executed in the perticular time>,from <data dictionary tablename>               -- I assume we can get columns as specified.
Where <TIME> bewteen <from> and <to>;

So the basic need is that i should be able to view the SQL which consumes heavy resources and the no. of. times that SQL gets executed in that particular time frame or session.

Thanks in advance.