Once the agent service accounts have sufficient privileges, it should be able to fetch the backups by itself

This is a historical bug that goes back to the original Sybase days

its most likely a security issue in SQL Server

Good programmers use the MERGE statement instead because it catch the cardinality errors.

The problem is that I have no idea how to get to the sql command prompt from within Visual Studio.

To get the day out from the Login date use string functions