Here are some tips from me.
First ensure that SQL Server has Latin_1_General_CI_AS as db and server collation
Ensure that Network Service account has full control over source directory.
And ensure that you are using correct authentication mode for SQL server.
If something goes wrong don't hesitate to start over.
About virtual directory, it is very easy to change.
Just browse IIS Manager and delete virtual directory and recreate it and name it anything you want, for example > dev_484
Then go to SQL Server and connect to database and to Portal Alias table, find alias for localhost/Dotnetnuke_maintenance and change it to new alias > localhost /dev_484
Save changes and try to browse website again.
If needed check Visual Studio too and make same changes for virtual directory.
Well, i tried import and export tool for moving content between databases but its better to get ideas from a more experienced user.
Regards.