Display Oracle User id and Database Name in Report header!

Hi am new to CR. I have two questions:
1- I am using oracle 10g and able to connect.
How can i display Oracle User id and Database Name in the report header.

2- I have big sql statement which is my report basis.
Can i write other small sql statements which that return a value and display in one of the columns the way you do in Oracle Reports.

Thanks
-Samsam1 Use parameters
2 Use stored procedure and design the report based on that