What Technique To Use To Update Production Table From Staging Table

Hi I have a production table in SQL Server 2005 that has approx 500,000 records---every 6 hours this table needs to be truncated and filled

The basic SSIS package uses a script compentant and imports the data into a staging table which has the same structure as the production table. I have a final Execute SQL Task that Truncates the production table and does a Insert into production-select * from stage table.

Takes around 30 seconds to run this last Execute SQL Task--problem is there is a risk that our webservice will query this table during the Execute SQL Task and return incorrect results.

Q1: In this last Execute SQL Task if I used a BEGIN TRANSACTION and COMMIT TRANSACTION; will this be any quicker ?

Q2: In this last Execute SQL Task- would it be better to use a RENAME TABLE technique in TSQL--any code examples ??

Q3:Is there any way in TSQL I can compare EVERY FIELD in two tables ie Stage and Production which have identical data structures and figure out a way to update only the records that changed? Is SQL Server Replication the best way to do this



thanks kindly

Dave