sp_rename[
^]
You can find the tables and procedures in the sysobjects table.
As for changing all of the references to tables within the stored procedures that will be more difficult. T-SQL isn't the best for string editing. You could create a managed stored procedure and use C# to handle this part.
However, the best approach, IMO, would be to use VS Database edition, or similar tool, if you have it so you could maintain a script and be able to rollback in case anything goes wrong.