Often the customer calls me because, when he tries to use the application (by entering username and password) after some seconds he gets an error message like "User does not...

As a matter of fact, if I open up a Command Prompt on my SQL Server, I can manually issue the SC commands I show above, and can START and...

Use DBCC SHRINKDATABASE OR DBCC SHRINKFILE.

I've never seen that error occur when expanding nodes within Object Explorer.

You can use Activity Monitor (under Management node in explorer) to quickly view resource usage among each user connections....

No, I don't have any experience with compression. Surely there is some formula to it though. I imagine performance would be an issue once your tables reached a specific size.

Data Archival is generally a business requirement that is considered during database design. It is only one of many variables that affect good DB design.

Before providing my solution, I have...

As the pervious poster asked, what is the purpose? Remember, there are always multiple ways to accomplish a task in SQL. It is the end result/goal that dictates the best...