We need to design more than 500 Reports for our ongoing project and we are dealing with MS SQL Server 2005 Reporting Services first time. We are currently confused in 2 things

1) How to manage Reports? I mean we should store entire report in database and load at runtime or simply store as a report file
2) Most Important is Dynamic Columns & Dynamic Grouping.
We need something like Microsoft Office Accounting 2007 Reports. Header part of form has some parameters for filter and right part has some parameters for showing or hiding and reordering columns and groups.
We are not getting clue for this dynamic stuff. Can any one post working sample or at least necessary basic code with some idea?

Thanks lot